Let the ringtone/remix fun begin! From NASA today:

Here's a collection of NASA sounds from historic spaceflights and current missions. You can hear the roar of a space shuttle launch or Neil Armstrong's "One small step for (a) man, one giant leap for mankind" every time you get a phone call. Or, you can hear the memorable words "Houston, we've had a problem," every time you make an error on your computer.

Here are audio files in both MP3 and M4R (iPhone) formats.

I will never forget hearing this one, the sound of the space shuttle launching, with my own ears.