Some are trademark related which is understandable. Then there are some (adchoices.com, acmespot.com or alittleaboutme.com) which resemble domain squatting and finally some random ones (aardvarkim.com and as13949.net) that just doesn't make sense.
Since none of these are active, what a waste of domains!
AS13949.com would likely be a reference to AS13949, owned by markmonitor
I don't know what that has to do with google.. but it makes some sense.
Aardvark was a search-by-IM engine that was acquired by Google in 2010.
I'll bite. I get understand why Google would own domains that collide with their trademarks, but what's with the totally random ones?
Possibly they came along with one of the numerous google acquisitions? It's not uncommon for companies to own a pile of relatively random domains registered by early staff.
It's generally seen as easier to just leave them be than sort out what has value and what doesn't.. and given google's size, 8000 odd domains is nothing.