Personal finance writer J.D. Roth keeps on top of his credit card spending by deducting his card balance from his cheque account register as soon as he makes a purchase.
One reason I got into [debt]trouble before was the lack of immediate feedback about how much had been charged to my credit cards. The spending was invisible and painless. Now when I plug numbers into Quicken at the end of the day, I make two entries for each credit card transaction: one to the credit card account, and one to a “dummy entry” in the cheque account.
Whether you use Quicken, a spreadsheet or a dead tree account register, this sounds like a good way to make yourself feel the impact of a credit card purchase as you make each one, instead of getting slapped silly with an aggregate “oh crap” payment at the end of the month.