Enhancing your Browser

How about stuff built in to your browser?

Google Toolbar: http://toolbar.google.com/ 

NBCi QuickClick (formerly Flyswat): http://www.quickclick.com/  

Alexa: http://toolbar.google.com/ 

What is a "Browser Helper Object (BHO)? http://msdn.microsoft.com/library/default.asp?URL=/library/techart/bho.htm 

More browser enhancements:
http://www.apps.com/category.asp?catid=230 

Browser enhancements from Google's web directory

Atomica (formerly GuruNet): http://www.atomica.com/