I am advertising in a few places and find for the same price I get really different results. Not because of targeting but I assume primarily it's based on how much traffic they get divided by how many other advertisements they are running. For my site I'm looking specifically for wholesale/home business sites but this is more of a general question. What sites have you advertised on that have had the best results (traffic wise)... and what sites should be avoided?
I know this may not be the case for most people, but I've found that advertising on the Sitepoint marketplace's "Advertise your Services" along with the $19.99 upgrade for a front page listing really works wonders. Probably 75% of my clients for ForumShock all mention seeing, hearing, or being referred to us by someone or something on Sitepoint - be it a written review, word of mouth, or my stickied post.