I don't keep a running count of any of my collections. The numbers are daunting even if its just something tiny, like say Petites, that fit all in a single small box or whatever. Its way less stressful without keeping track of numbers!
I have a Shutterfly site where I keep track of my collections though, more or less. I take photos as I get new items. For dolls and action figures, I have lists of each brand and when I got them. For ponies, I just upload the photos into yearly albums. The photos are captioned with info like the pony's name, how I acquired them, and when they arrived. I might need to find a new way to organize since we're getting to the point of a year album with 2 photos in it.
With the dolls I just add a note to the lists when I get rid of something but for the ponies I basically did nothing about it ever. I think I'm going to photograph all my ponies on white and make new albums for my current collection, sorted by generation. That way I can keep the visual history of the old albums that I enjoy and still have an actually helpful area that shows all the ponies in my collection. But that's sooo cluttered... it might be time to just ax the old albums. I may enjoy them from a nostalgia and time capsule sort of view but they're honestly terrible! The photos are almost entirely horrid, haha.