Sleeper - actually some of the number/letter combos (3letter) have sold for some pretty impressive prices so I wouldnt say they are of no value - if someone is willing to pay in the thousands for those then my guess is that they are of value to someone
TPat - when I talk about brokering I kinda lump all of the services like SEDO, etc into one ball of wax - there are a few brokering services that do all of the pushing for you but they tend to take a much bigger cut of the sell price as they are actively doing things to push for you. I would use those types of brokers for extremely high end type domains - although Ive always just dome my own and let someone like SEDO handle the transactions - and they are one of the good ones for parking. There are a few better - Ill get together a little list for ya