Hayao Miyazaki's Gilligan's Island

Best Lost theory that I've heard in a long time: the giant amorphous cloud-monster is a swarm of nanobots. Credit to ISCA's Kilgore Trout.

Second best: Locke's Dad is the original Mr. Sawyer.

Update
Best Lost spin-off idea: Locke and Eko are drag queen roomies. Thanks to Farker TLBreer.