Jonathan - 9:11 pm on Aug 6, 2010 (gmt 0)
Some of those "featured site" listings in directories are shady, as they don't adequately communicate the fact that they are paid placement.
If you're already going to the trouble of personally reviewing sites and categorizing them, it's probably best to just leave them in some default order, or hand-pick the best ones and list them at the top. The traffic and linkbacks you get for the increased quality of your directory page will likely be more valuable than any "featured site" listing fees you may be able to collect.
Also, to increase your long tail traffic, use varying keywords in your titles and descriptions, and avoid filler words.
BAD: This site features information on widgets, and more.
GOOD: Photographs, diagrams, and details on blue widgets, Canadian widgets, fixing widgets, how to make widgets, and widget alternatives. Also includes a chart for identifying and dating antique widgets from the 1920's and 30's.