I have an idea of making a virtual market (aka prediction market, derivative trading...) where people will be able to bet on pretty much anything.
Particularly, stock market prices. E.g. if you believe that AMD stock price will be at least 9 in a month you can do this by making futures/options contracts. Then virtual exchange monitors real exchange and does settlement: awards profits to ones who won (at cost of ones who lost).
The thing is I've already implemented this for exchange rate speculations (see http://forum.bitcoin.org/index.php?topic=14059.0
) but it all depends on what 'spot price' is, so it can be easily transformed into arbitrary virtual market.
Of course, it also needs a simple front end which allows people to make a simple bets. E.g. "I bet 25 BTC on AMD market price higher than 9 in a month", literally. This will be translated into futures contract or an option. And expert users will be able to work with those futures/options directly.
But I wonder whether people are interested in this stuff... I've seen moderate interest in futures trading, but when I've actually launched it it currently has just one user who deposited 0.03 BTC.
I don't quite get WTF happens, either people see it as not reputable enough (but hey, 0.01 BTC isn't a big sum to lose, right?), or they are not interested because they all bet on BTC by buying them. (BitOptions is pretty much empty too, so I guess the later...)
Anyway, if you'd like to see virtual market please donate to this address 12xN4yB53aigoHqu1ES2m1ihGxyvFCswSk
or deposit money into my futures exchange and post a comment. Even if it is just 0.01 BTC I still would appreciate that.
I could consider open sourcing the thing, but my current code base is in Common Lisp so I doubt anybody's going to use it