jelly vibes are generally soft rubber or some similar feeling product. they flex when you push them, while the one's I prefer are "stiff" if you'll excuse the double meaning.
You can also see jelly sleeves over hard vibes. I've read they're harder to keep clean, though. Non-porus is the way to to! easy cleanup
edit:
other internet good toy shops:
http://goodvibes.com/
http://www.adameve.com/