The two indispensable toolbars in your web-surfing.

PageRank Toolbar from Google:
It returns page ranking rated by Google when you visit a particular website’s page
http://toolbar.google.com

Alexa Toolbar from Alexa.com
It returns the traffic ranking of a particular website you visit
http://download.alexa.com/index.cgi

Alex does not offer toolbar compatible with Firefox. If you use Firefox, please refer to their information page to install 3rd party Alexa toolbarfor Firefox:
http://www.alexa.com/site/help/?index=127

Get used to using them in your web browsing. You’ll soon get yourself the power to distinguish good sites from bad ones.