I'm not sure if this has already been mentioned, but I use tonethis to get my ringtones. I have an LG VX5200 from Verizon, and it has been working fine for me. I use wavepad to edit my mp3 to make it short like a ringtone, save the file as an mp3, start up tonethis, convert the file, then upload it. The cool thing about wavepad is that you can amplify the ringtone to make it louder before you upload it through tonethis.
If you want longer ringtones, using bitpim with a data cord is the best route to go...It's the only program that's bypassed Verizon's 25 second limit.