Hope this hasn't been posted before. Sorry in advance if it's a re-post.
I posted this link in another thread but didn't want it to get lost.
If you're interested in creating your own custom voice ringtones have a look at this site: http://www.research.att.com/projects/tts/demo.html
You can create tones saying anything you want and choose from a variety of voices.
Once you've created the tone and previewed it just download it. Then simply convert the file from .wav to whatever your BB uses (in my case I used DB Powe AMP to change it to Mp3.)
I've loaded a dozen or so of these onto my BB and they work great. I mostly use things like "it's XXX calling." With the contacts that call me most often I know who's calling before I ever look at the BB.