This is in the wrong forum... but anyway, I think people are looking at the X letter domains wrong.
I don't care about random 4 letters with no meaning, such as WKDQ.com (no offense if somebody happends to have that one.. lol, I am just picking a random 4 letter name).
However, 4 letter words and pronounceable terms that can be branded ARE in fact rare, and should be considered a different category than just 4 letter domains..
LOAN.com anybody? How about eBay.com... iPod.com, XBOX.com, FORD.com, DELL.com, SONY.com, IMAX.com... I could go on and on, but domains like those are worth a lot BEFORE being branded. Heck, a few years ago XBOX didn't exist. Microsoft bought the domain name from someone who probably registered it because they thought it sounded "cool." Well COOL.com is worth more than dks.com and other random 3 character acronym names.