For just the camera I have a Zing neoprene cover.
For the camera with an extra lens and extra batteries I have the Crumpler 4 Million Dollar Home.
For everything (3 primes, 2 zooms, flash, K-x, batteries, cleaning supplies) I just ordered a
Dolica GS-300 from NewEgg on sale for $20 (with a free smaller bag and 4GB memory card) that I'm hoping will be suitable storage for my whole kit, which I rarely take out all at once. I'll report back. I couldn't find many reviews on that particular bag but the sale price and timing were just right. Hopefully it won't be terrible.