Drag the grey box to your bookmarks bar. When you're on Facebook, click it, and the text goes bigger!

Big Text!


Use Greasemonkey?

Then head along to UserScripts and hit install. It will run everytime you visit Facebook! Awesome.

Thanks to Mike for pointing this out.

FAQ

Don't have a bookmarks toolbar?

Try something like View - Toolbars - Bookmars

Uh, what now?

Drag it to your toolbar. Or right click on the box, and choose something along the lines of 'bookmark this link'

Do I have to do it every time?

If you use the bookmarklet, yes, if you use the greasemonkey scripts, no.