Are there any handy animation addons out there?

Hi Guys,

I’ve been animating more with blender and loving it.
I was wondering if there were any addons not listed on the site that are so useful that they should be.

One thing I have been looking for, is some kind of script to better illustrate (in the timeline) how many keys are on a frame.

Currently blender shows the user whether there are keyframes on a frame. However, it would be nice, if the ticks were thicker if there were more keyframes on one frame, and thinner when there were less.

Is there anything like that out there?