Well, this is a nice addition to the Island theme. Hmm.... My six occupations would be

1) To become completely fluent in another language. Here on the crowded mainland I would like to know Spanish better than I do, but since I will be all alone on the island, I think learning classical Greek might be more edifying. Reading Homer in the original. . . ah, those dactylic hexameters shouted out to the moon, wafting on the tradewinds to the stars. . .

2) Karate. There's probably little chance that I'd get mugged, but one can't be too sure these days.

3) Become a theoretical physicist. Every time I watch NOVA on PBS I think I've wasted my life.

4) I agree with John. Learning music would be great. I'd love to be able to read a Beethovan symphony.

5) Finally learn how to ski. A dubious skill on a desert island to be sure, but maybe some genii might fly by and create the illusion of the Wasatch for me.

6) Learn to converse with animals.