I use a "bridge" camera, a Fujifilm Finepix S100FS. This has the weight and bulk of some SLRs. I simply put mine in a padded camera bag, I chose one that's a tight fit so bits don't rattle around inside. I then "throw" my camera, in its bag, into my pannier or tank-bag. The latter is very convenient, I can stop, unzip the tank-bag, unzip the top of the camera bag and just take out the camera.
The bag is a
Loweprow, lots of nice pockets and stuff, shower proof as is, but has a built-in rain cover as well.
(Click on image for larger view)
More pics
here.