Guys, I'm currently developing a cloud bot which supports an inter-exchange arbitrage (at the btc-e example). It's totally cloud-based, which means that you administrate it via the client admin panel, but your own bot process runs on the GoDaddy dedicated server. What's more, you can fully control it: manually start or kill your bot process on the server, get real-time logs, change trading strategy. Now I'm involved in tests & fixes to advance it's built-in strategies and in further development to make it perform custom strategies using simple formulas on basic variables, such as volume delta (time period, abs or rel), price delta (time period, abs or rel).
Cheers

Paypal is centralized. Every drawback comes from this premise. On the contrary, decentralized structures like Bitcoin don't possess a magic ability to absorb money into themselves.

You can also fund a project and start a bitcoin crowdfunding. All you need is an idea.

Buying & selling huge BTC-amounts when it was 10$ per ea. No B&H strategy, so this punished me (and lots of us as well).

However, if an automatic conversion to a fiat currency is needed, things become far more complex. In this case you need an integration with a payment gateway API, which may take time + there are usual formalities

Blockchain API is ridiculously simple (demanding simple authentication if needed and returning trivial JSON responses); therefore, any programmer can easily implement logic to let the user download a software product upon receiving the 3-rd confirmation of users's Bitcoin payment. I have personally made it work in my ASP.NET Web App.

Exchanges can't actually add decimal values in their databases as it will lead to theit clients' funds unsecurity (there will be a negative delta between assets and liabilities) and they will have troubles while processing crypto- or fiat withdrawals as there won't be enough money. Great exchanges (especially today's leaders) possess internal terminals to control this figures in real time (at least our exchange had  ).

I believe it's great to diversify risks by storing/investing fiat in various instruments, such as bonds and shares. Bank deposit, as the most conservative option, should also be respected. I also use fiat to trade futures.

Just the same, writing my own .NET sharp lib to communicate with popular exchanges. Had run into some problems with JObjects in a few responses - however, gonna solve it pretty soon. It's inconvenient to work with responses like this one:
              <...>,
   "return":{
      "343152":{
         <...>
      }
   }

Total time logged in: 45 minutes... from this acc

Звучит очень красиво, но на деле много не заработаешь. Потестите ещё пож-та. К сожалению, иногда биржи вовсе не дают вывести какую-то конкретную крипту.