yup. this is a handy site to search for expired domains. sometimes you can get some good 4 llll ones http://www.findeteer.com
cool, but find some which are more likely to spell the abbreviations of some lawfirm or real estate company
btw ... i am the owner of avuw.com and that list is reaaallly old like over a year. Blog, could you edit your post since that url doesn't even exist anymore. Avuw is now a cool exchange, check it out ... if you dare
Maybe this thread on the domain name analysis will give some more ideas, http://www.nameslot.com/Domain-name-analysis-t-1297.html
I own some four letter domains but before I bought them I check them in Google. If I found the four letters in a lot of sites then it was worth the risk to me. I find they are very slow to sale. Now that I hear they are rapidly being registered I will keep them for a few more years.