After seeing one of their info-commercials on TV I plugged a reviews inquiry into goggle.com.
Found alot of reviews and bbs threads from those who had bought these things. Overall, the units seem to work, mildly. The biggest complaints was with cheap construction (they start failing in a couple months) and difficulty in getting them attached properly.
Wide price range, too. (The $40
Fast Abs seems to work as well as the $100
AbTronics.)
Go here to compare price/performance on the various brands:
FitnessInformercialReview