Gotta go with Damon. I spend very little time on Miranda though (which seems to be mostly folks banned from DPReview). I hang and socialize on DPReview, but all the REAL TECH questions get asked on Galbraith (helps that Canon's US Tech Support head monitors the Canon groups)...
Luminous-landscape.com is good, if you can handle Reichmanns obtuse way of writing, but the 3 mentioned above are probably the top 3 general boards (aside from like the sportsshooter.com board, and other genre specific photo boards).
Rick