Some songs just weren't meant to be ringtones. That said, i personally don't think ANY song was meant to be a "ringtone." A phone should ring; I can understand having different rings for different phones, but all the ringtones I hear now really irritate me. Some kids have ringtones of loud, obnoxious rap songs that were meant to be played with a significant amount of bass; instead, on the phone, it sounds like a bad version of a song you might record off of the radio to a cassette.
On top of everything, my phone NEVER makes a noise. It is always on vibrate; I see no good reason to worry about annoying people in theaters and restaurants, because I sure as hell am annoyed by their phones. If I'm in a restaurant, and my phone starts vibrating, i may sneak a peek to see who is called, but I would never answer without excusing myself and going outside. Who do people think they are talking on their cell phones in restaurants? Are you kidding me? And these people have "phone voices" that are much louder than their normal voices.
Geez, after all that, my conclusion is that mobile phones are destroying society.
And to answer the question, just go to your service provider's website for normal rings; Verizon, Cingular, T-Mobile, whatever.