Well as a matter of fact - I even created a credit card ledger similar to a checkbook ledger using a spreadsheet, to carry in my wallet. I have one line for every $5 of our budget for the week. Every time I make a purchase I cross out the appropriate number of lines and note where I spent the money and tuck the reciepts in behind the ledger. Then at the end of the week I check my cards activity online against my ledger and make a bank transfer.
This may sound extreme, but I found out the hard way spending could get out of hand with credit cards, but those reward cards are so tempting. Now if I could just figure out a way to pay my sons' tuition on the Visa - even more points!