Must have FireFox extension for Web Masters
 

http://chrispederick.com/work/web-developer/

This is an amazing extension and has been a lot of help to me.
It has a lot features related to css,cookies,images and more.
Install it and check it out.You might find some tool which you had dreamed of.

This is my favorite Firefox toolbar. I use it both at work and at home. I very highly recommend it to anyone working with building web pages. :tu:

Thanks :) I've downloaded it. Very cool tool!

I love this extension, I've used it since it came out. Although, when I installed FireFox 3 Beta, I was no longer able to use it - until now. I'm glad he released an update.

:kickass:

This is a great tool
 

I have been using it to validate my pages for quite long.

Specially validating CSS is of great use in this tool.

hm looks interesting :)