I'm surprised so many of you mentioned .org! I don't use that extension much.
I only use .com for non-proxy sites. I use .info for some proxy sites. I put up one proxy site on .co.cc but lists have so many restrictions that I'm not going to do that again. I have one .co.uk domain for a proxy site.
I am investing in the following domain extensions:
.com, .info, .in
com/net/org get the exact match keyword bonus from Google, so those are the ones I use.
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I swear, by my life and my love of it, that I will never live for the sake of another man, nor ask another man to live for mine.