One of my biggest punctuation peeves showed up on the back of a Restoration Hardware catalog:
Use AOL keyword: Restoration Hardware or visit restorationhardware.com.
The colon is used to set off the keyword, but the sentence keeps going instead of ending after the thought is complete. The entire post-colon thought (Restoration Hardware or visit . . .) makes no sense. Because use and visit are split apart by the divisive colon, the parallel (use this or visit that) becomes meaningless.
Use AOL keyword Restoration Hardware or visit restorationhardware.com.