For a fresh, free, and geeky source of ring tones, it’s tough to beat WolframTones, a musical mashup of Wolfram Alpha and Mathematica that generates unique ringtones based on algorithms.
Visit the site, start tinkering with the settings, and WolframTones will generate a ringtone (and several variations) for you based on the style you’ve selected. The defaults for the various styles–classic, dance, blues, etc.–are great but you can delve into additional settings for further customization. During our test, for example, we were messing around with the “signalling” category and by going into the instrumentation panel we could pick which instruments we wanted as part of our alert-style signal ringtone.
After generating a ringtone you can download it, save it (free account signup required), and/or email the results to a friend. Hit up the link below to take it for a test drive.