it works on me, definately. especially on my lower belly and belly button area and sides, if my hands are tied (worse if above my head in order to stretch my tummy) and if i'm expecting it will tickle :P
belly is a very weak spot for me too. bellybutton included of course!! fingers (wiggling or little squeezing), tounge, raspberries are all terrific tools and even feathers get me there when i'm tied.
for the bellybutton i would name also q-tips and electric tootbrushes
this ;)
and I can confirm that a) pedicures do tickle; b) pedicures make feet more ticklish, definately.
I liked the original post, reminded of me and my husband :)