Light is a word of many meanings.  It could be the lightest in color or the lightest in its impact on the interface of your browser.  I have done my best to find the lightest popular Firefox 3 themes that would fit into either dictionary definition.
Whitehart - I never did use this theme until [...]

Running out of room in your bookmarks toolbar?  You could do some spring cleaning - but winter is quickly coming upon us.  Next idea?  Well the Smart Bookmarks Bar add-on for Firefox promises to simplify your cluttered bookmark rat’s nest.
 
It shrinks your bookmarks down to only the favicons.  So what?  Well, the magic happens [...]

Now when it comes to using a browser, some people like a lot of open space and others like to have a plethora of tool bars. Personally I find myself in the first camp - most of the time. That is why I was happy to see this new Hide Menubar extension roll [...]

When it comes to themes for Firefox, you should know by now that I like them to be easy on the eyes and I like for them to be simple. When you mix those two needs together, you can for sure get the Industrial Firefox theme. This will give your browser a slick [...]

Kemplton is definately a clean and familiar Firefox theme.
I have been using it on my notebook PC for a while now, and I can not say I have any real complaints. A lot of the icons and navigation of it look much like the standard themes you see out there. It [...]

Sure you have heard of trimming the tree around Christmas time, but what about trimming your browser? The folks over at CyberNet have done it again, producing one heck of a nice guide to cutting the slack from your Firefox experience.
Firefox is a truly amazing browser and I think my favorite part about it [...]

If you use either the Greasemonkey or Stylish Firefox extensions, I have the perfect extension for you when it comes to getting a little more browsing room while using Google Reader.
Just load this bad boy up via either one of those extensions and you should be good to go.
So where does it save [...]

Here is another good theme that has been made for the Firefox 2 general layout. The designer of this theme describes it as a Clean modern theme for Firefox 2. A nice alternative to the default theme since the colors are lighter and easier on the eyes. I don’t know about you, but [...]

It has been a while since I changed my Firefox theme. I have been using Mostly Crystal most of the time these days, but I thought I would look around and see if I could find a different one I liked. That is when I decided to take a trip to Planet Mir [...]