can you delete keyframes at regular intervals in a given range? the BVH I imported has keyframes on almost every frame.. i want to edit like 300 frames and i want 1 keyframe for every 30 frames for those 300.. Im currently doing it by placing 2 markers between 29frames and selecting everything between them adn deleting it... but i have to do this 10 times.. is there a better way?
It's not exactly what you're asking for, but maybe it can help : there is an (integrated) addon, Simplify Curves. It reduces the number of keyframes, preserving the general shape of the curve.


Activate the addon (search "simplify" and click the checkbox next to "Add Curve: Simplify Curves") 
Select your F-curves
type Spacebar then "simplify", select "simplify F-curve"
adjust the "distance error" setting. Warning, it's located in the Operator panel in the 3d view, not in the F-Curve editor