Greased Lightbox
Some of you use greasemonkey (an add-in ‘scripting tool’ that lets you customize how other pages work in firefox).
For those of you who don’t, there are hundreds of scripts out there that change the behavior of pages you use every day. For instance, there’s one that gives you “quick comment” next to “comment” in LJ, and clicking gives you a little box to fill out, rather than loading a new page.
There is an add-in for greasemonkey called Greased Lightbox. I’ve been using it for awhile on my work computer, and let me just say, maaaan it is so much cooler than the default behavior for images.
Whenever you click on a link that leads directly to an image (such as with google image search), it instead pops it up in front of the window you’re browsing, on a transparent black background, with easy buttons to zoom in and out, plus easy links for going forward and back amongst image links on that page, and if you click anywhere but those buttons, it goes away, rather than leaving you messing around with a new tab.
So if you do a lot of looking at images, consider using it. I forget it’s there until I go to someone else’s computer where it isn’t, ’cause it makes firefox behave just like I think it should.

I kinda like the better gmail script, tho I don’t take too much advantage of everything it offers.. I do like that it show what kind of attachment an email has.
There is a better Gmail firefox extension, as well as Better G-cal. I really like the “Gmail Redesigned” skin you can get with Better Gmail.
Nice script. Here’s a handy link to it.
Does Greased Lightbox burn up the quarter mile, though? :-)
I’ve had issues with Lightbox and Flash, but it’s certainly a pretty cool idea.