If you own a site and is currently selling advertisements manually, you may want to consider using AdSella to help you sell and manage your advertisements. I joined AdSella last week and put up a listing for my web design site and the listing was sold early this week.
The thing I like about AdSella is that I do not have to manually upload the banner =) The banner is being uploaded and managed by AdSella. In long term, this allows me to focus on the development of the site rather than the administrative work and staying in contact with the Advertisers. AdSella charge a commission of 20% off the total rate and I think it is fair as it is one of the lowest when compared to its competitors.
AdSella also has a blog that talks about listings that has high impressions helping your site to gain additional exposure. My listing was featured in their blog post this week.
Not only you can sell your advertisements, you can also buy advertisements from the listing if you are looking to promote your site. They categorized the listing according to PageRank and impressions making it faster for buyers to identify their target market. Although AdSella is pretty new, I think it has a lot of potential to grow especially for low to mid range websites. Give it a try and share your results here =)