I "clean" my commuter chain by dragging the chain through a filthy rag, then heavily oiling the chain, then repeating the drag through the rag again. That's as clean and oiled as it's going to get.

For bikes I buy off craigslist to work on...if I tear it completely down to bare frame, I'll fill up a water bottle full of simple green, drop the chain in there, give it a good shake, leave it for a couple days, then give it a scrub with a nylon brush, then another dunk in the simple green to dissolve some of the gunk, then rinse with water, then spritz with wd40. Once that evaporates, it gets a generous oiling, followed by a wipe with the rag. This is only for clearly nasty looking a neglected looking chains though.