Came across a nifty toolbar when I was browsing http://mozdev.org
Its called Stumble Upon The base line says “Word of mouth Web”
StumbleUpon allows you to “stumble upon” great sites that have been highly recommended by friends and community members with interests similar to your own.
It is a very interesting concept and I did stumble upon interesting pages like this one
But be warned – After Swati installed it on her Mozilla 1.0 for Linux the browser refused to start, however it runs perfectly on my Mozilla 1.3b on WinXP as well as Linux