Something I've seen in other fandoms is people choosing songs that suit various characters, mostly due to the lyrics.

So I thought, why not try starting one here, to see what ideas other people bring up.

To kick things off, here's one that I think suits Wash rather well:
http://www.youtube.com/watch?v=-vgfeLat3RI

Lyrics

I can't really explain my reasoning terribly well - there are just a few lines that really seem to reflect Wash in this song, especially if you substitute the water connotations for space.