A classic is interrogation, but if you're trying to "spice things up", the 'ler has already probably tied you down and extracted information from you and then continued to tickle you afterwards for taking so much time to talk, so:
1) "Tickle Me" Just tie the 'lee down and make him/her say "tickle me." There are a lot of variations. Most 'lees want it, but saying you want it is surprisingly difficult.
2) Holding a pose while being tickled is hard, especially if it exposes something vulnerable.
3) Doing something else while being tickled can be interesting. A popular option is reading a book (people also do this with masturbation -- try to read while dealing with a vibrator or whatever). I used to tickle an ex-girlfriend while she was trying to play piano, and of course there were consequences for mistakes.
4) If you're versatile, see who can hold the longest while being tickled and then punish the loser
5) I have liked quizzing restrained 'lees and choosing my next action based on their degree of correctness. Adapt to fit.