I have been using a GoPro Hero 3 Black, and it's a great camera, but it's obnoxious mounted to the bill of a cap. I think I'm going to replace it with one of these: http://www.tachyoninc.com/sportshooting.html
rumor is that gopro is coming out with Gopro 4 in June. Seems to solve some of the problems of the 3+ and is supposed to be smaller and have better battery life. I would wait a month and see.
Contour is another good brand that isn't quite as expensive as GoPro. Light weight, easy to use, good picture quality. UCOshooter knows more about them.
Contour is awesome, but they went out of business in August 2013. However, the business was purchased and the products are supposedly available again. Some retailers still show their products as discontinued. Luis has one, and I like it better than my GoPro.
Yea I love my contour light and easy to use with great picture!! Just so many different options out there, but for the money I would suggest the contour!