Well, in school we talked so much about tuning, I even took a class that devoted part of it to MySQL tuning, but I had yet to see a need for it until today. We have a site that wanted an area to each video page that pulled in content like Amazon.com. We titled the area "People who viewed this also viewed" and we were pulling in content that was seen by other users and highly rated. So, here's the sql I came up with:
SELECT path, COUNT(path) as count FROM accesslog WHERE uid IN (SELECT uid FROM accesslog WHERE path='*****' AND uid !=0) GROUP BY path ORDER BY count