|I use the Macsense GeoMet'r, and I've been pretty happy with it. It seems to be pretty similar to the Nikon one (which I haven't seen in person, but have read about quite a bit).
The GeoMet'r seems to acquire the satellites pretty quickly, and has been a good, non-obtrusive unit for me. I bought one last November, and the power switch eventually stopped working (probably partially due to me sticking it back in the camera bag attached to the camera?). They gave me no grief about it when I wrote to the company... they swapped it out with a brand new one.
Like the Nikon one, it uses the camera's battery, so it's definitely important to shut it off when not in use. It doesn't shut off when the camera is off.
Here's a review of it.
I will add that the Geotagging software that comes with it is pretty crappy, but there's some much better stuff out there. Nikon's ViewNX does a really nice job with it, actually.
Message edited by author 2009-10-10 21:26:45.