So many to choose from. Pretty much every girl in Lucky Star, Tooru and Run from A-Channel, Ran and Kazuha from Detective Conan, and too many girls from Pokemon to count.
Integra Hellsing. There is just something about her that I can't explain and I think she is hot. I'm pretty sure she'd have to be tied down and I'd want Alucard to help me.
When I was younger I wanted to tickle Kagome from Inuyasha and May from Pokemon. More recently I thought about how satisfying it would be to tickle Korra from Avatar, assuming I don't get a firey boulder hurled at my head.