bitaddress or any other wallet or code that you use to generate a key pair will give you 2 things:
1. a private key which is starting with the letter L or K or number 5
2. a base58 encoded string known as bitcoin address starting with 1 or 3.
you only need number 2 to check the balance. you can simply use an online block explorer to check the balance or use any wallet that supports "watch only addresses" to import your number 2 in and check its balance.
there is also a nearly new method which some wallets use which is known as HD wallets. these generate a Seed for you. these wallets give you two things:
1. a master private key or your seed.
2. a master public key
you can use the number 2 to import into your online wallet and have a "watch only wallet" containing all your addresses instead of importing each address one by one.
example:
http://docs.electrum.org/en/latest/coldstorage.html#create-a-watching-only-version-of-your-wallet
