The other day I asked how to get nearly free and easy mail accounts. Turns out Gmail does it.
Add a + after your name and then add any string you like.
dave.winer+hello@gmail.com
You can also add or omit periods in the middle of your name.
dave.winer@gmail.com
d.a.v.e.wi.n.e.r@gmail.com
davewiner@gmail.com
See the writeup on the Google blog from 2008.