I'd prefer it if people used their phone's (least annoying) default tone, but I know that some users can't resist fiddling around. Here's hoping those people will check out iRingPro.
Billed as "...smart, attractive, livable alerts," these aren't your nephew's ringtones. Instead, you get a serene but noticeable series of notes that won't elicit strange looks in the board room. Additionally, the pause between repetitions is longer than most, eliminating that sense of "I've got to answers this now!" urgency. There are few samples you can check out on the site, and they're quite nice.
A collection of 21 tones in M4R format will run you $9.95US. Please, if you're the downloading type, consider iRingPro.
Alternatively, you can try your hand at making your own classy tones with GarageBand.
[Via The Iconfactory]