AdBrite
700 websites

AdBrite is free to use

http://adbrite.com

AdBrite labels itself as the internet's ad marketplace. It provides interstitials and banner ads on a cost per mille (thousand) basis, and text ads on either cost per click or cost per action.

VS

Tailsweep
103 websites

Tailsweep is free to use

http://www.tailsweep.com/

Tailsweep: The advertising network for blogs and social media.

Market Share by Top Websites

1 AdBrite is leading in Top 1M Sites and The Entire Web.

2 In terms of market share, Tailsweep is clearly lagging behind, losing to AdBrite in all segments.

Websites Categories

1 AdBrite has better usage coverage in more websites categories. Including Computers Electronics & Technology, Arts & Entertainment, Adult, Science & Education and 16 other categories.

2 Tailsweep is leading in Food & Drink and Home & Garden.

Geography

1 AdBrite is leading in most countries, including United States, India, United Kingdom, Philippines and 66 other countries.

2 Tailsweep is leading in Sweden and Lithuania.