Sony, Garmin and Tomtom all do a gps camcorder. The Tomtom looks to be the best of the bunch.
A cheaper option is the Gobandit GPS HD. Gobandit went out of business a year ago and it is no longer possible to down load GoBandit studio from their website. As a result, no body wants the Gobandit any more and they can be bought super cheap.
I bought the original 720p version for £25 on ebay, and recently bought the later1080i version for £50, also on ebay.
GoBandit studio enables you to add gps overlays and is very very easy to use. Luckily for me, I had downloaded GoBandit studio just before they went out of business. If any body needs a copy, I can email it to you.
The clip below is the older 720i, I have not used the 1080i version as yet. The main difference between the Gobandit and Garmin etc, is the Gobandit shows your peak speed and current speed. The other manufactures only show current speed.