Use the Multiple Compete Rank Checker tool to check the Compete rank for several sites at once. Compete is similar to Alexa in that it uses its own toolbar to gather data about websites. Compete, however, also draws on other sources such as ISPs and opt-in panels to create a more comprehensive ranking system.
Compete was started in 2000, so it's been around long enough to gain significant momentum among ranking sites. With this tool, you can easily find out the Compete rank for multiple sites, whether your own or those of competitors. It's also another great resource to use when considering a site purchase or online advertising.