I am building an application for which I wish users to be given a unique address to which they can freely deposit funds into their account. Meanwhile, I want to be able to both track their balance and use the bitcoins they've given me. Their balance is effectively the total amount of bitcoins that their assigned address has ever received (regardless of if the coins have been spent) minus whatever I've charged them, and I need a way to determine the first bit.
Also, my server does not have enough storage space to use bitcoind, so I've been using electrum, though I'm fine using another piece of software or even a web api so long as it's reasonably secure.