You all know at DU you have to donate to use the search function. At the top of the page is a little google toolbar that lets you search the site.
It doesn't seem to work quite as well from what I've been told. I usually go to Google and include site:DemocraticUnderground.com in any of my searches if I want to see if the Little Goons have discussed anything of interest recently. At least Google will let you restrict your searches to a particular time frame (>24 hours, a week, a month).