Welcome to FT!

I'd start by reading the stickies in the Mileage Run Discussion forum: http://www.flyertalk.com/forum/forumdisplay.php?f=627

Then I'd also keep an eye on the Mileage Run Deals forum:
http://www.flyertalk.com/forum/forumdisplay.php?f=372


Good luck and good MR hunting!