1) Beta test.

For example, the Firefox and Chrome nightlies:

http://nightly.mozilla.org/

http://tools.google.com/dlpage/chromesxs

A couple million hackers can help "upgrade" the Internet every day.

2) Ask/answer questions. You're making it a lot easier for the next guy.

How can I do X in Linux?

http://superuser.com/

http://askubuntu.com/

How can I do Y in Gimp?

How can I do Z in Inkscape?

http://graphicdesign.stackexchange.com/