object dissappear

how would you go about making an object dissappear at a certain frame within an animation? I tried animating the alpha value, but that did nothing.

well, animating the alpha will make something transparent, so you might have missed a setting. see http://wiki.blender.org/index.php/Manual/Raytraced_Transparency

Another way to make something pop off is to animate it’s layer channel and have it switch over to an unrendered layer.