Printing Business Cards

Now that I’m self-employed, I need to get some business cards printed up.

Anyone use a place they would recommend? I don’t care where it is as long as they do quality work (and will work via web/e-mail/phone if they aren’t in the Denver area).

I’m not looking for a huge quantity at this point so a print-on-demand set-up is probably preferred. I’m also willing to discuss a trade services/barter situation.