Fisher isn't kidding when they say that their 20- and 24-inch PreCaliber (20", $320; 24", $360; fisherbikes.com) models give "rock star status to little rippers." Unlike a lot of kid mountain bikes, the PreCaliber is specifically designed for girls who want to ride off road. Fisher built it using the same Gold Series aluminum frame technology they use in adult bikes, and both the 20- and 24-inch versions come with 50-ml. travel forks and SRAM 3.0 components. All this geeky technospeak means that this black and pearl-blue bike will provide you with hours of fun and durable off-road riding.
One thing: If you're pretty serious about mountain biking, don't let your parents talk you into a bigger bike that you can "grow into" three years from now. Mountain biking can be pretty intimidating and if you buy a bike that's too big, it might make you less confident, which will give you a disadvantage when trying to smoke your dad.