Tribulus terrestris is the #1 selling testosterone booster, and the best example of a supplement that increases libido, but has no effect on testosterone.
Ab belts may cause muscle contractions if used properly. But the belt alone cannot produce six-pack abs. The real challenge to ab definition is the layer of fat that lies right under the skin, hiding muscle tone.
The Ab Rocket works very well and is easy to assemble and use. It gets your abs looking great with only 5-10 minutes of work each day. The only drawback is that it comes with only 3 levels of resistance. I used the lowest level for a day or two, skipped level 2, and have been using the highest resistance ever since.