I tell you this with an odd mixture of glee (it's fast! it's efficient!) and embarrassment (I'm not certain if it's gross or not. Something tells me it might be, but I can't pinpoint the exact source of the actual potential grossness.)
Lisa Lisa, a character in Po Bronson's novel Bombadiers (Catch-22 based in San Francisco's financial district) can run four miles in 28 minutes, and when she gets home, she showers in her running clothes, then swishes them around to rinse out the soap.
I thought of this a few weeks ago when it looked like I was drowning under a pile of sweaty Cool-Max, and tried it out.
Washing your clothes in the shower rocks. Go and do it right after your next run. Seriously. Here's what happens: You wash them while you wear them, then rinse them under the shower. If you wear tech fabrics, they dry really really fast. They seem to get really clean: I was initially skeptical until I smelled them the next day (yes, I sniffed my shorts. Shut up.) and was greeted with nothing more offensive than Irish Breeze. (Shut up!) And - this is anecdotal, but it kinda makes sense - handwashing in the shower seemed to restore all the original wicking properties that tend to disappear after multiple machine washings and dryings.