Tom Cruise, Kevin Spacey, and Britney Spears all show up in "Austin Powers in Goldmember". Meanwhile Cruise's ex-director and co-star Cameron Crowe and Cameron Diaz turn up in a subway scene in "Minority Report".

It's that old cinematic staple - the celebrity cameo, something that has titillated film nerds ever since Alfred Hitchcock started inserting himself into every one of his movies.

But while some are obvious, like Charlton Heston stepping in as a world-weary gas station attendant in "Wayne's World II", or David Duchovny as a conspiracy theorist in "Zoolander", others - and this makes it fun - are slightly harder to spot.

For instance, did you catch Glenn Close in "Hook"? No? Well, that's probably because she strapped on a 'tache to play one of the Captain's cronies. And next time you watch the cult Chevy Chase/Dan Ackroyd classic "Spies Like Us", look out for the morose double act of directors Joel Coen and Sam Raimi. They're the guards carrying machine guns outside the baddie's secret compound.

Of course, cameos also give cruddy stars a chance for big-screen glory. Witness therefore, Screech from Saved by the Bell in "Made" and Mr. T in "Inspector Gadget".

More importantly, cameos might be appearances that future stars would rather forget. Keep that in mind next time you switch on streetwise epic "Breakin'" (aka "Breakdance: The Movie"). While bodypoppers like Aldofo 'Shabbadoo' Quinones are doing their thing on the beach, you should be able to spot a young man who's stumbled over from Muscle Beach wearing a black, short-legged unitard giving it some attitude and dancing like he's at G.A.Y. None other than Monsieur Jean-Claude Van Damme.

So put on your geek spectacles and get spotting.