Audacity rocks, is all I can say. Just added the spin-up and spin-down effects to "Vampire Megabyte". Cool.
After experimenting unsuccessfully with various samples of a tablesaw spinning up and down, I decided to work directly in Audacity. Spin-up started with a 3-second sawtooth chirp going from 110Hz to 880Hz. I then applied a couple of distortion-type effects (with very little success), followed by gverb. That worked, very nicely.
After that it was just a combination of pitch and tempo changes to stretch it out to the right length. The spin-down was, of course, a shorter chirp in the opposite direction.
Oh, ok. If you're geeky enough to have read this far, here.
I'd still like some modem tones, somewhere around 300 baud. Which is something Audacity doesn't do, alas. May require advanced fakery. Or a real modem -- got one of those...