<3 Rated 5 out of 5 stars
This is one of the best add-ons that exist and the sheer volume of scripts already made just makes it that much better. The possibilities are endless with GM. If you can think it you can do it! GM & Photoshop is the reason I started learning JS.
Also to the reviewer that says GM is slowing down FF you should check your scripts especially if you have anything that's adblock related or having to monitor page text.
Some of the scripts with sloppy coding can greatly reduce your browsers reaction time.
Still what other add-on can you have auto click your links by the page,edit the css,play video games for you,check your spelling,block ads,turn text into links,pop out your image previews,resize your video player,keep inactive tabs active,change tabs when a timed download is ready,change to the next page when you hit the bottom,merge all pages into one page,change the page colors,create a bazillion tools to embed into any site or have pop out always on top, and whatever else you can think off ALL IN ONE ADD-ON!
"Yes I know there are other add-ons like GM now but I don't care about them. :P"
I <3 GM! The 5 stars I give it just feels too low if you ask me.