So besides side-swiping into a guard rail (see thread titled "The Worst Happened..."), I noticed something else when driving my banged up 3000GT. The speedometer goes all over the place sometimes. It'll flicker up and down, up and down, sometimes all the way to 10 miles above or below my actual speed. Then it'll be normal again. And then it'll go haywire again. On and off, on and off, anyone know what this is? How to fix it?

It sounds to me like your dash might have a loose ground as a result of the crash. The speedo on my old Prelude did the same thing, but the odometer still kept good numbers.