Originally Posted by TheDoc

I like Alexa... I don't use it as my end all tool, but it's a great place to start your research.

Any site with history, ranking, and a steady graph is almost always a solid site to do a trade with or some type of business with. On the flip side, if you have a 100k rank site, and you open a 10m rank site, it's really not even worth taking a second look at past Alexa - for trades.

It's also good to use to compare equal/related sites with. Like Affiliate Programs that don't host the galleries on the aff domain... With known equal factors, you can see which ones get the most traffic, then you know which sites to research for traffic sources.