Few post back I told you about how to make browser toolbar. I found one more resource to have your own custom toolbar.
Alexa, the famous traffic rank company, lets you have their toolbar custom to make it yours and also earn money through its amazon search engine. You can not fully custom the toolbar however you can add your name and logo to it to make it look yours. You can also add your amazon referal id to its search engine and earn some money by sending some buyers to amazon.com.
To make a custom toolbar you have to make a xml file as described by alexa and place it on your web server and let the alexa know where the file is and you have your custom toolbar ready to distribute.