Thumbs up for arms up! I consider ticklish underarms every bit as sexy as ticklish feet, and will happily exploit either, depending on which is more sensitive on a particular `lee.
I don't currently have a specific file for underarm-specific shots, but I may just have to create one to be able to join in on this revered thread. Gimme some time on that, though. I'm arse up in other projects at the moment. You can bet I'll be checking in and saving much of the stuff you(and anybody else, hopefully) happen to add!