Seems nearly two years since I learned about myxer.com and I'm glad to say it's still functioning and still free. You identify your cellphone (their files apparently will work with any model and service), upload your own music clips, edit the clip to a 60-second file (used to be longer) and send it to your phone as a ringtone. The cost is whatever you pay your service for receiving a media file (could be part of your package, or likely 10¢ or 25¢). I used it to customize my first cellphone (yes, came to them rather late) so completely that I had a different ring for every family member and good friend. Since that phone died, I've never gotten around to remaking and reloading so many tones, but it's very nice to hear Albinoni when my phone rings, instead of those horrible synthesizer tones. OK, so I'm fussy about sounds (too). Elgar's Salut d'amour played when my parents phoned, isn't that sweet? Now they have separate phones and when Mom calls I hear, "Oui, c'est elle, c'est la diesse" in the caressing tones of Bizet's The Pearl Fishers (Les pêcheurs de perles). I used to have a clip of Handel's Arrival of the Queen of Sheba identifying B&B arrivals: hey, it's joyous music, nothing more intended.
You can download the files to your computer as well as send them to your phone, and of course I wish I had, so that I wouldn't have to remake them all after the first phone failed. The trick is, once you get the file ready, go ahead and send it to your phone, but then hit your browser's back button so you still have the ready file and can send it to your computer (which costs nothing). I like to play a music clip with Windows Media Player or any other that lets me watch the timeline, so that before sending the clip to Myxer, I can write down a couple of good starting points for the ringtone, keeping in mind that 60 seconds is all that can follow. Then, at Myxer, I can put in a starting time, listen to see that it's OK, and run through it a few times to set a good stopping point. The interface is the usual pair of sliders and a count window, typical for sound or video editing. Couldn't be easier.
So, help eliminate cellphone noise pollution. Put some good music on your phone!