The 52mm 2x tele lens from Soligor is a very new one. I don't know whether you can get it in the USA, if so, I think it will become a very wanted object. It is rather cheap (official price 129€/$) and constantly produces very sharp pics. See for your self... (I only have one real test shot with/without converter, I will be adding more of them very soon I hope)

Pros:
-very sharp images
-cheap
-you can buy it directly from Soligor (www.soligor.com)
-a very nice 2x magnification
-Soligor has their own adaptor tubes for most digitals (including the qv4000 and the G2)
-also a direct mount on Raynox's RT5247

Cons:
-at f/2.0 a litle bit of vignetting around the corners; not much and it disapears entirely at higher f-stops
-no direct mount on Casio's 58 mm LU-35A adaptor (step down ring will produce more vignetting)
-I can't screw my close-up lenses in between because their lenses are pressed against the back of the tele lens than (could be because I use old macro lenses from my analog SLR)