Buy the .net and .org as well?

and maybe more

[StoutFiles]

If I have a popular .com name, how important or crucial would it be to pick up the other extensions as well if they're there?

[buckworks]

If they're available, grab them.

Domains are cheap and having control of the obvious variants could save you a lot of headaches with squatters and copycat wannabe's down the road.

[King_Fisher]

If its a hot name buy them all up, including various spellings that are close.

...KF

[dailypress]

it will give you a peace of mind that no one else will copy. I think its worth it for valuable domains or sites that you put a lot of work in.