When it's warm, I use a power washer. If I can't use the power washer, I don't clean. As noted above, ain't nobody got time for dat.
I just rinsed my bike in the bathtub. I think I got the idea from some old thread somewhere on these boards. I'm hardly fastidious, but my bike was getting seriously salt and crud encrusted. My work space is on the roof, but with the arctic temperatures and getting home after dark, not to mention general laziness, that wasn't happening, so I just gave it a good dousing under the shower. It did a pretty good job of rinsing off the crud, and the tub didn't get particularly dirty either. I also try to give the rims a wipe after riding through the slushy crap, to get the sludge off.
My bike is an 8 year old Walmart bike on original tires, original chain, original, well, everything except for the tubes I replaced at the end of summer. Nothing gets cleaned on it.
The most cleaning it had was last spring when the chain was completely rusted and frozen up solid from my daughter leaving it out in the backyard in the snow and rain last winter. Soaked the chain down with PB Blaster for 2 days, got the cranks spinning again, and she rode it around the yard all summer. At the end of summer, I put the 2 tubes in the tires and I did take the derailleurs and brakes all apart and cleaned them. Still the same 8 year old frayed cables along with the same worn out sprockets and rusted and worn chain and I started riding it for exercise. Rode 500+ miles before the time change and work schedule pulled me off.
I'll probably jump on it for one last time here this weekend as I take my wife's SUV up for a state inspection and ride the Walmart job home. By next week I'll have the tax refund and hopefully a Giant Escape 1 heading my way. Of course, this one I will keep it clean, though I just realized this is in the commuting forum and I'm not a commuter. I still need to learn how to keep the new bike clean though.
Please tell me if I'm right: I think the most important part to clean frequently is the rims and brake pads (for rim brakes), to ensure the brakes will work properly. So almost after every ride I wipe the rims clean and insert a damp paper towel between brake pad and the rim for a minimal cleaning at least. I try to keep the rims free of greases and mud.
My bike doesn't get dirty enough to need a hose down. Once or twice a month I bring it down to the basement, wipe it down, and lube.
I regret not taking the hose to my bike on Saturday. I just went over it with a wet and dry rag and there is still grit in the crevasses that a hose would get to. I'm careful about the bearings and mostly aim at the gritty parts. Then wipe down. I'm not sure what to do with my chain though as it is brand new with the factory lube. I guess if I hose it I should lube it.