Nice classified ads site.
Also that adbrite full page ads ad is annoying and a big turnoff for me. If I wasn't reviewing your website, I wouldn't submit a listing and leave. Get rid of the full page ads and to make extra money charge a small fee to make someones ad highlighted or to stick out a lot better then the rest. You might get people to upgrade there listing to this new feature and make some money.
The contact page link is in the footer and should also be in the header up top so it's easily seen by people. Since I see no about us page, or submission rules page, i'm sure people want to ask you questions before they actually signup.