If your phone's ringtones just aren't doing it for you anymore, or if everyone at work is sick of that one MP3 snippet, WolframTones can generate original, 8-bit-sounding ringtones based on genres you select and send them to your phone.
WolframTones works by defining a set of loose criteria for each musical genre (such as classical, dance, jazz and hip hop), and then generating a random MIDI tune every time you hit that genre's button. It works remarkably well — the tones are not a jumbled mess, they actually contain a melody and tend to (mostly) fit the genre you selected. Plus, each time you click it, you'll get something new, and probably never get the same one twice.
There are some more advanced features, like showing variations of your currently generated tone, as well as even changing the instruments on each track within the tone. You can also change the musical scale, tempo and duration. It's pretty cool if you're sick of your ringtone, or your phone only supports MIDI. And, of course, it's all free — though standard messaging rates will apply when you send a tone to your phone.