Chris Gonzales at Tools & Toys turned me on to these great ringtones for iPhone. Previously, I'd use the default tone, or alternate between a couple Linkin Park songs. That was okay, but I wanted something more understated and minimal. Well, I've been using Cleartones for a few weeks now, and they're terrific. I went for the set of 50 tones for $10. Download them, import into iTunes, and sync to your phone. Worked like a charm, and I won't be going back to the stock tones or song-based ones.
If you're looking for some cool ringtones, I highly recommend checking these out.