I ride my bike in the rain a lot and don't really do anything special to clean and dry it at the end of the day -- I just hang it up. I do, however, keep the moving parts lubricated. Pretty much the only place I see rust creeping in is on the bolts that hold my rack and fenders on and the water bottle bolts. I pretty much tolerate it there, though I do remove them once in a while and grease the threads.

If I hang a bike up with a wet chain and don't ride it for a few months, some surface rust will often show up there. This happens, for instance, if I forget to lube the chain after washing it. In this case, a fresh application of oil is usually enough to get rid of the visible rust. The chain life is probably shortened, but I don't replace it just because I saw rust. I wait for it to be worn.