motion tracking in FCPX

I’m working on a preso about motion tracking, and I hope you all can offer some expert feedback. Now that we have various solutions for motion tracking in FCPX, I wonder what kinds of things people are tracking, and which tools you choose to do it:

Do you use Motion’s built-in tracker?
Do you use a FCPX motion tracking plug-in, and if so, which ones?
Do you use a separate application outside of FCPX and/or Motion?
What kind of footage do you track?
What kind of effects are you making with that tracking data?
Any other reasons why you use motion tracking in your workflows?

Thanks for all of your help!

Double post?