I'm riding and racing HED Jets (60/90 combo) & really like them -- responsive, noticably faster (based on TT results) and sturdy. At first I had planned to use them just for racing, but swapping out wheels was sort of a pain (or I'm just really lazy ... maybe a bit of both) & I've now used them extensively for training and racing for 2+ years & they're still true. They're heavier than Zipps, of course, but the Zipps were far out of my price range.

Beyond the more traditional aero wheel manufacturers, you might want to check out Williams Cycling. Their disc is made by Zipp & their aero wheels look pretty sweet too. Especially at the advertised prices. So far in 2008, tThere have been several articles and reviews featuring Williams' wheels ... all of the ones I have read were very positive.

Happy shopping :)