Pastie is the paste site I've been waiting for. Simple, elegant, useful, fast. Now, I've gone a step further and (re)written a shell script to paste from stdin and give you the URL:

#!/bin/sh
curl http://pastie.caboo.se/pastes/create \
-H "Expect:" \
-F "paste[parser]=plaintext" \
-F "paste[body]=<-" \
-s -L -o /dev/null -w "%{url_effective}")

But that wasn't far enough. I went one step further and made an OS X Automator workflow to take what's on the clipboard, paste it to pastie, and put the resulting URL on the clipboard. Throw Pastie.app in ~/Applications and you can use Quicksilver for the perfect instant pasting panacea.