i have a Nokia 3300 and it has a 64mb memory card on it so i just edit mp3's and upload them via usb my current ringers are Sevendust-Face to Face and Mudvayne-Happy
Currently I'm using a sound sample from PGR3.
The one with the F355 going through the gears.
It sounds great! Even coming from the (somewhat) crappy speaker on my phone!
Although the volume on my phone is a lot louder then what most phones can handle. (It's a nokia 6230)