I regularly sing the praises of Mint, a free site that makes it easy to manage your finances online [1], so when I heard about their latest feature — text message alerts of your account balances — I couldn't wait to try it out.
If you're already signed-up to Mint, just text BAL or BALANCE to MyMint (696-468) and Mint will send you the balances from all of your bank accounts [2] that you track in your Mint account.
Now you won't have any excuses about over-spending when you're out shopping!