If we're talking professional only:
A whole bunch of the tickling paradise video auditions--even though they're only 30 seconds or so, they were some of the first I saw. Cricket, Deedee, Erin, Dena, and JEnna come to mind.
Tickleabuse: Goth Abuse, co-worker with nails, and revenge.
Tohachi the amazon being tickled
An LOL video. I forget who's being tickled, but she's in nylons, and just when it starts, she shrieks "Oh nooooo" before bursting into full throated laughter. Rihanna maybe?
LIlah Rose being tickled on Boston Tickling. (She's a friend of mine, and she's an awesome person).
Miss Ticklish USA.
And a very honorable mention to Ryan Conner, facedown on a comforter blurting out "All's I can see is this fuckin' teddy bear!!!"