.com is here to stay, don't let anybody tell you anything different followed by .net, .org, .us. biz, .co.uk and .info.
This of course is dependent on the name itself as some names just don't work with with the extensions .org, .biz and .info.
For example casino.org all though a great name will not be as powerful as casino.biz. This of course is only my personal opinion.