In my case, while I have something like 6 or 7 active cards, I don't end up using each one every month... it all depends on what I'm buying. But as for juggling due dates, I use Yodlee MoneyCenter. If you bank with Bank of America, Fidelity, HSBC, etc. then you've seen their licensed versions of Yodlee's product... I just use it direct from the source. It's a great timesaver. (Search the forums for "yodlee" for more info, or just visit the site!) No, I do not get a kickback.