Great site, it's gonna be useful.
Maybe in the future you could make it possible to just input addresses and it would read the exact balance from the blockchain. It's a bit tedious to calculate everything first if someone uses plenty of addresses and does lots of transactions. It's a great site thought, good job.
already tried to do this, I tried to take a shortcut and use the API from places like
http://blockchain.info,
http://explorer.litecoin.net and the other ABE based block chain explorers...
Doing it this way would make it easier to code, but also make my site depend on more other sites to be up and running.
The problem is that only blockchain.info supports addressbalance with a confirmations parameter.
https://github.com/jtobey/bitcoin-abe/blob/master/TODO.txt The todo list lists addressbalance so its not yet implemented, with no mention of a confirmations querystring.
Once I discovered that I would need to look in to the actual network (like a wallet?) to get the information for each transaction, for each coin I unfortunately put it in the to hard basket (for now).