Really handy workaround for the buggy Web Rated 5 out of 5 stars
At some point in the development of the Web, developers gave up on accessibility in favour of fixed-pixel designs.
NoSquint lets you work around how each individual site breaks differently (or doesn't) when font size is increased. It leaves Firefox's full-page zoom enabled by default, but lets you use ctrl+SHIFT+plus/minus to change the font size instead. It sounds like such a little thing, but I really appreciate it.
The first-run screen is pretty well-implemented as well. There are a couple of extra features. E.g. it adds zoom buttons to the toolbar - but the first-run screen tells you it's one that, and gives you a nice convenient button to remove them.