Two more ideas. At some point, consider the Chase Freedom, no fee card. There used to be more generous signup bonuses, up to 35K, but for the last year or so, the bonus has been 10K. The key here is the rolling quarterly bonus spending categories, which give you up to 7500 Ultimate Rewards points per quarter or 30K per year. You'll need to hold onto your CSP or have some other UR participating card so that you can convert your points to UR. I'd keep an eye on the bonus with this card--if you see it go up, consider jumping on it then.

An illustration of a good shopping portal deal right now is the magazines.com bonus through the United MileagePlus shopping mall. 35 miles per dollar. Get a two-year subscription to Sports Illustrated for $78 and earn about 2700 United miles.

Signup bonuses for credit cards are the highest single method of earning miles in any program, but I figure anything that can get you 500-1000 at a pop for free or 2-3K for spending a minimal amount of money is worth taking a look at. Of course, if you're just trying to extend the life of your miles, then almost anything that earns or burns miles is worth it.