Ok I know how to make an animation cyclic, but is there anyway to tell blender to start cyclic animation on a certain frame or stop on a certain frame? Or do I just need to duplicate the animation and stack them up?
Cyclic? You mean it ends at the starting point?
I find the best way for me is to copy all animation data (IPOs, poses etc) from the first frame to one frame after the end, then wherever you move things throughout, they’ll always find their way back by the end all ready to go again!
Or do you mean things that cycle several times in an animation like a fan blade spinning or a character walking?
Hmmm - Re-reading your post I think you mean the latter. What are you animating? Is it something simple like a spinning object or a bouncing ball? or more complex like a walk cycle?
maybe he can get to know the nla editor
You can use an IPO driver. This way, the actual animation is controlled by a secondary object, just like a switch.
Set up the cyclic IPO as normal then apply a driver object (N-Key over the IPO window). You can set the IPO to function when the driver object is rotated, for example, then you actually animate and key the driver.
Thanks andy, that seems to work out well.
Phew! 
I’ve got a strange feeling someone (bugman?) wrote a script that was also aimed at solving this problem. It was a few months ago and searching could take a bit of effort - plus I could be wrong.