Still loving the service! But not sure how this could be done but some way of having trades associated to the API job use the local exchange rate (of the API) and then have.
Eg
MtGox API - Buy 1 btc @ 250USD
BTCe API - Buy 1 btc @ 220USD
Then prices go up 10% the Profit/Loss would show $50 with MtGox and $44 with BTCe, when infact it should be $47 ($25+$22)
Hope this makes sense

Also +1 for an Android Balance App

Keep up the good work Dario!!
Yes, that does make sense. However, I do not know any financial site, the works on this principle.
There is
only one reference price. Whether for gold, stocks, commodities or Pork Bellies :-)
With Bitcoins, it is of course somewhat different.
I have set the reference rate to Mt.Gox in my account.
For that reason, that I always sell at GOX, since they have the best course.
So if I buy cheap BTC at BTC-E and transfer them to GOX, I have already made profit automatically, because the price is usually better at GOX.
If you want to evaluate your purchases of BTC-E and GOX individually, you need two accounts.
In one account you trackst then your BTC-E trades, and in the other the GOX trades.
Under Settings you can connect both accounts by the way, but still choose a different course in each account.
Hope this helps

PS: An Android APP will come in December!