What do you think about the JVC wide angle adapter? Does anyone have another brand's adapter?

A little more info might help: Which adapter for which camera are you talking about?

Oh right. I am talking about the HM100 adapter that was really just the JVC Everio adapter.

I used 46mm Canon (0.7x) and I liked it. It doesn't produce much distortion. The big draw-back of the adapter is the fact you can't mount screw-on filter to the front of the lens. Bower also makes 0.5x 46mm lens, but this one will give you some fisheye effect, some like it some don't. The advantage is you can screw on a filter to the front of the converter. While making your decision just remember HM100 has only one setting for ND filter, which will lower your F-stop by 1/10. If you shoot outside, with lots of light (like on snow) you'll need to be able to use ND filter attached to you lens. JVC's lens is selling for $215 at B&H, it's too much imo.
I also found this: http://www.bhphotovideo.com/bnh/controller/home?O=NavBar&A=getItemDetail&Q=&sku=420280&is=REG&si=rev#specifications . It is a 49mm converter, but there is a 46 to 49mm step up ring. 119 bucs for the converter and 16.95 for the ring, seems like much better deal then 225 of jvc. And it does have the front thread as well.

Oh right. I am talking about the HM100 adapter that was really just the JVC Everio adapter.

I bought this adapter with the camera. Seems fine - a little bit blurry on the end of the zoom but i did not buy it to use like that. No way to accept filters so a matte box might be on the cards, or you might order (like me) a clamp on lens shade to suit.

Using it wide seems fine - I'm not a pixel peeper, but it seems pretty good WRT barrel distortion. No complaints. Needs flagging like any wide lens does in bright sun. Great in close quarters with subjects just a few feet away. Seemed a bit pricey but business purchase.

HTH

Cotty