Most of my photos never end up being processed; they just sit there in RAW format unless I decide to process them for display in a web gallery. Although I'm much more assiduous about assigning keywords these days I agree with a point that Doug raised; I need to be more "ruthless" in making culls. I have 1.5 terabytes of storage at hand, but that can still be used up. (And this is on the 40D; when/if I finally make the jump to a 5 series full frame... oy!
) If I'm in any way undecided I mark it as a Reject in Bridge so that when the time comes to do a cull I can find them easily.
For the ones that
are processed, though, it depends on how much processing needs to be done. If it's nothing more than a quick "crop and convert" I'll just keep the RAW and the resulting .jpg. If it's something more extensive then I'll save as a .psd first and keep that as well. I haven't done any printing yet, but when /if I do I can't discount using other formats as well, depending on what the printer advises.