Agree with dvestors. I've had many 4 letters before and most were never good for anything more than reselling to other domainers. I can only think of two of them off the top of my head that did receive offers, ATWS.com and ATOT.com. Anything with Q, Y, Z in them should immediately be discarded. I don't ever think will see a day when YZQX.com sells for a minimum of $500 or $1,000 just because it's 4 letters long. I still don't see the value in 3 letter .coms like YZQ.com either. They can't possibly be good for anything but reselling to other domain investors. The fact that most of the 3 letter .coms still being bought and sold today contain 1 or more of those characters strongly supports this point as well. If there were big companies that could utilize such names they would have bought them up long ago. For the 4 letters, acronyms that end in CO, C, S, etc.. are worth looking into. If google results and overture searches look outstanding then they are worth registering and hanging on to. Otherwise, don't bother. They are a highly selective investment.