F6 - go to web address in FireFox [and IE too, i think) <-- yep, also works for IE

Alt + Tab - to switch windows (Left to Right)
Alt + Shift + Tab - reverse switching of windows (Right to Left) also works on text fields

Alt + Space + X - maximize active window
Alt + Space + R - restore active window (when maximized)

If I use this
F11 - full-screen toggle in FireFox
It chops of the title bar & the menu bar (with all my bookmarks on it

@Lighthouse: I think that is what full screen is designed to do. Use as much screen space as possible to display the web page.
F11 does the same thing in Internet Explorer. Though I think it has options for what toolbars are displayed in full screen mode.

jack7h3r1pp3r, I use the Ctrl-Ins/Del, Shift-Ins for copy, cut, paste because that's what I learned first and I've been using them for a long time. I don't even know the origin of these, but I think it goes way back to some old text editor or word processor from the DOS years. Wordstar, maybe? Anyway, it's easier for me to find these keys without looking because they are on the edge of a block of other keys. If you have been using ctrl- c/x/v for a long time, maybe you can find them without looking, but I can't.

here is one i found out by accident in fire fox here it is hold ctrl + scroll wheel (on mouse) make the font bigger or smaller not sure if this works in ie though

This does work in IE and also in Explorer and in Photo Gallery, Word 2007, etc. I use it sometimes too.

It's handy for when I've forgotten my glasses :)

It's handy in other instances too. E.g. you look something up in Wikipedia that comes with these small drawings. Normally you cannot read the writing on it, but magnified it works. For details on pictures too.

Just a note on Ctrl+Scroll Wheel: The effect can be different in different programs/versions.
In Internet Explorer 7 and Firefox 3 it zooms the page including the font and pictures.
In Firefox 2, Internet Explorer 6 and lower it just changes the text size, no pictures or anything else is zoomed.
Also for Firefox 2 and 3 you can use Ctrl+Shift+Plus for up and Ctrl+Minus to go down.

Edit: Updated from tests. Apparently the zoom is new to IE7 and FF3 copies that feature.
Edit 2: Just did another test. It appears Opera 9 has a zoom feature too. I'll have to see which came first.
Edit 3: So far it appears Opera did the zoom first then IE7 and now FF3. Now weather a browser did a zoom before Opera.
Edit 4: I just looked and found a small list of programs with an actual zoom at http://en.wikipedia.org/wiki/Page_zooming

It's mostly user preference though Opera does do some things better then other browsers.
So far I think Opera loads pages faster and has some things builtin you need extensions for to get with Firefox.
I still prefer Firefox as it has an interface that can be customized a lot more.