This:
But maybe I'm misunderstanding, the wording is a little bit confusing.

So wait, this is called "No Forced TX Fee" but it still forces TX fees in some cases? Is there any client that REALLY doesn't force transaction fees?

You could create and sign (but not send) multiple transactions from your address to another specific address in various amounts and then carry those instead of your actual private key. That's the only way I can think of, and it's kind of cumbersome.

Well it's certainly had it's share of problems recently on that front, hasn't it? I realize that mostly related to using it in the web browser, rather than with local programs, but security is definitely a concern. I also dislike how aggressively Oracle pushes their propriety version and how even open source projects seemingly go along with this (i.e. "For best results, use with Oracle" etc.). And finally, it's a trivial gripe, but I do prefer native applications just for the sake of not having to install yet another support package.

So no, surprisingly I meant what I actually said. But now that you mention it, Java programs do tend to have crap UIs. I can't comment on whether this applies to the bitcoinj based clients mentioned above as I have not tried them. I may yet do so considering the dearth of appealing clients in general.

I see. Yes I think that was the distinction I was missing.

I recently had some bitcoins stuck in unconfirmed limbo for a while, it's taken care of, but it got me thinking... could the following happen?

1AAA is a bitcoin address. It contains 10 BTC.
I attempt to send all of it to 1BBB, but for whatever reason, this doesn't make it into the blockchain.
Presumably I'd notice that, but maybe I'm in a hurry and plan to deal with it later.
In the mean time: 1CCC sends another 1 BTC to 1AAA.
And I try to send half of that on to 1DDD.
My client believes 1AAA only contains 1 BTC so...
It would go something like txin=1AAA txout=1DDD:0.5 txout=1EEE:0.5 (the latter being my change)
But the rest of the network thinks 1AAA has 11 BTC in it so...
"Hey they didn't mention these 10 BTC, it must our fee, yay!"

Would Bitcoin-qt actually do this? If not, what steps does it take to avoid this situation?

First and foremost, the wallet of my dreams must never impose ANY restrictions on the user. It can warn that what I'm going might be rejected by the network, but it should always always let me do it, no matter how stupid it thinks my request is.

Second, the wallet of my dreams would definitely not depend on Java.

While that might be good advice, it wasn't really the point. I  just wanted to understand how this works better in case it came up. You're right though, the classic client really is looking increasingly clunky.

Thanks. I decided it would make more sense to go with the minimum that works, instead of worrying about all that.

How about this scheme then:

I sell you a whole crate of bananas for USD, then buy it back from you for BTC. Both transactions would be at a reasonable market rate (slightly in my favor, natch), and if you want to stop after the first step and keep the bananas, of course you're entitled.

Would that still be too "cute"?

So to answer the last part of my question I did a little experimentation myself. It seems if I copy just the block subfolder (including blocks/index) it still takes ages to start up, well at least an hour, I lost patience after that. But if I copy blocks/ and chainstate/ it starts up reasonably fast. Just a few minutes.

So I guess that's what I'd do if this ever comes up. No one can think of any problem with sharing the chainstate folder, right?

That does make me feel a bit more confident. If all the obvious stuff is in there, presumably it's not also any other files.

Yeah, I knew that much already. But still when dealing with computer security such I'd rather be too careful than not careful enough. So I don't want the copy linked to me in any way. For instance, I could easily imagine that some of those files might have my personal spend transactions recorded in a different order since my client knows about them before anyone else. (No idea if that's actually true, but that's the kind of thing I'm wondering about.) I like the fact that Bitcoin is pseudonymous, and want to keep it that way.

I realize of course that if I seriously got in the habit of handing out copies of this stuff I could simply make a clean install and download the whole monster database again. This is mostly hypothetical (although I could see it happening) I just feel uncomfortable having this huge chunk of data and not knowing whether I should regard any of it as sensitive or not. It's like I've got my house key attached to a car tire plus a half dozen other bits and bobs that I don't completely understand the use of.

I'm trying to figure out which files used by Bitcoin-qt relate to my personal "accounts" and which only relate to the blockchain and such. I've read the data directory wiki article (and the Stack Exchange post it links to), but I found parts of the explanation somewhat less than enlightening.

Obviously I know what wallet.dat is, and I know that's the only file I absolutely need to back up, or copy if I'm moving to a new machine. But does it contain all of "my stuff"? Like the names I've assigned to certain addresses and such?

I'm also interested in the reverse situation. Say I want to set an acquaintance up with a ready to go bitcoin-qt install and save him the annoyance of waiting for it to sync. What's the minimum I can copy and save him a bunch of time. Are just the blk*.dat files enough? And conversely, is there anything other than wallet.dat that I should definitely not copy? Since (hypothetically) I don't know him that well, I would want to ensure no trace at all of my personal bitcoin activity is left behind.

Sorry if this is all a bit noobish, but I've looked around and I haven't found a really clear answer anywhere.

This is a one time job, first response gets it. (Post or PM)

Basically I just need someone to send me a screenshot of how MMS displays on an iPhone (any model, but no UI hacks please). There's a tiny bit more too it, but not much. You won't have to give me your number, but you may need access to a second cellphone of some kind.

Job as been completed. Thanks, both of you.

You know what the biggest reason this is a terrible idea is? It doesn't even accomplish anything. Consider SatoshiDice, the biggest "offender" when it comes to noneconomic translations. All they've got to do is have people send an extra 0.001 BTC with their bet and send it back either with the winnings or alone if they lose. They could even throw in an extra satoshi for tradition sake.

Well, looks like they're attacking Bitcoin after all. No MtGox isn't Bitcoin, but it's obvious what this is about.

This is certainly alarming news, but so far I'm hopeful that it's only related to some specific money laundering case, or whatever. It would be very typical of the feds to do something like that without caring how many honest people they inconvenience.

Stupid idea. I'm not going to use this.

For what it's worth, I was able to withdraw BTC from my BitFloor account with no difficulty. Luckily I had no USD in my account (well, 34¢ actually). I imagine it will be a tense couple of days for anyone who had a large amount in there, but for the moment I see no reason to worry you won't get your money back.

Very disappointing though, IMHO this was the easiest exchange to use.

If I understand correctly (someone please correct me if not) any address you have used before copying the wallet will be perfectly accessible from either copy. As will any coins sent to those addresses, regardless of whether they were sent before or after the split. Speaking as a fairly new user myself, this I think is all most new users would expect, and that part is fine. What is not immediately apparent is that the wallet contains an additional 100 addresses pregenerated for later use. This means when you "add" a new address, it actually takes it from the pregenerated pool. The first 100 address* you add to one wallet will already exist in the copy. Handy, but not perfect. After you go through the 100 address*, then it has to start creating new ones, which won't be in the copy. That's still not terrible, but if you burn through 100 address* on both the original and the copy, then neither wallet will contain a complete set of addresses, that means some Bitcoins will only be available in one or the other (and some will be in both), which does sound like a rather confusing situation.
*I understand some are used up for behind-the-scenes purposes, so you shouldn't expect a full 100 to use directly yourself.

So (again, assuming I've understood all this right myself) it looks like all you would need to avoid these problems is to make one copy your "Primary" wallet, and regularly replace the others with fresh copies of it.

But there's another problem it won't fix. That pregenerated address pool can be helpful, but it can also get you in trouble. Because when you add a "new" address in one copy of the wallet it might already be one you used in a different copy. That could be confusing, e.g. if you unknowingly give the same address to but both Alice and Bob to accept a 5 BTC payment from each, and 5 BTC appears, you might at first thing they both paid, but then you realize it's the same address and you've only been paid once... but by whom?