For a while now I have always used default ringtones in my Blackberry 8120, which is supplied by my work. The problem is when someone else in the office has same ringtone set on their phone, thus confusion ensues.
That is why I have created my own custom ringer:
The original song was by Nina Simone, where it has appeared in several films and product commercials. Most recognizable ones are The Thomas Crown Affair in 1999 and recently in HTC's "You" campaign commercial. I used Audacity trimmed down a remix version of the song by Felix da Housecat.
Feel free to use the song, and let me know you think or what is your current ringtone.