Other Canon non-L lenses that don't suck:
From what I've heard, the Canon EF-S 10-22mm is built using some of the tech that goes into various L lenses, but because it is an EF-S lens they decided not to sell it as an L. I want one.
Also, I have had good luck with my 50mm f/1.8 in low light.
I think I'll eventually end up getting the 70-200mm f/4 L or the EF 70-300mm IS USM.