What are your favorite and most used Lion features?
My #1 in my list is the full screen mode, really helps me to concentrate on what I'm doing.
Launchpad is cool but I wish if it supports typing to find apps quickly instead of iOS style navigating.
Can't comment on AirDrop until I get an iPad :)
What is really missed IMHO is a notification system similar to iOS 5 one, hope the next cat (maybe a cat?) will bring it to the table.