this will probably sound a little foolish, but I do not know what the file types are for the ringers.
I was/am using www.3gupload.com
. Very cool site for ringers and more. I just noticed on there that they allow you to upload your own files and they have a little FAQ on creating "Voice Ringers". So you should check it out if you are interested. To use them, they basically text you (or you can just go to their website and view "your locker") a link to the files. You download the files from there and they automatically show up in your list of available tones inside the Profile section.
I have download some fun songs. I am still waiting for someone to come up with a custom ring per contact application, but I think there are still some API limitations there with the BB OS for the 7100.