Odigo combines the features of ICQ, Third Voice, Alexa and Gooey. It lets you see who else is visiting the web site you are at, presumably because thay have similar interests to you. You can then chat and send links or messages. It's likely to become as big as ICQ (which is rumoured to be dropped next month in favour of AOL Instant Messenger according to Glassdog).

From the help file:

"Odigo provides the perfect solution. No longer will you be alone when you surf the Net. As soon as you install Odigo, you become a member of the Odigo community of Internet users. While surfing, Odigo allows you to see and communicate with other Odigo users browsing in the same site or page as you. In this way, you can find and make contact with people who have similar interests to yours. Odigo also enables you to identify which are the most popular Web pages among Odigo users at the current moment, so that you can benefit from other people's surfing experience. You can go directly to any of these pages from your Odigo window, and find the users that are browsing in them."