please don't invest your hard earned money in random 4 letter domains. you will regret it. of course there's always the slim change that a company will want your 4letter domain because they need it for their abbreviation, but most likely you're throwing your money away. spend your $7 more wisely and go deep into the mines looking for gold. you'll find this hard to believe, but you'll have a better change selling 4-WORD domains than 4-letters.
look here for more info:
http://ww.gofuckyourself.com/showthr...pagen umber=1
GL