Here are four handy shortcuts that work identically in Internet Explorer and Firefox:
Save a favorite Web site
To add the current page to your list of Favorites (Internet Explorer) or bookmarks (Firefox), press Ctrl+D. You can move on to other pages, knowing that the location is saved for future reference. To recall the page, use the Favorites (IE) or Bookmarks (Firefox) menu.
Switch to full-screen view
Menus, toolbars, and other screen clutter can get in the way of some pages. Press F11 to turn on full-screen view, which hides everything except the toolbar and status bar. Press F11 again to restore the normal view. (You can also click the Restore icon in the top right corner of the screen to return to normal view.)
Change your home page
What’s your home page? If you don’t specify a preference, Microsoft sends you to its home portal, MSN. Firefox sends you to a custom Google page. But you can change your start page anytime. The slow way is to go through dialog boxes. Here’s the faster alternative: First, go to the Web site you want to use as your home page. Then click the icon in the Address bar, just to the left of the site’s URL, and drag that icon onto the Home button.
Move back to the last page
Your hands are on the keyboard and you want to quickly return to the previous page you were viewing in your browser window. Don’t move your hand to the mouse; instead, press the Backspace key, which has the same effect as the Back button on your browser’s toolbar.
Ed Bott 
Firefox and IE share quite a few shortcut keys.
Firefox/IE common keyboard shortcuts
by alphabetic key combo
Alt + D | Select Address Bar/
Location Bar
Alt + F4 | Close Window
Alt + Home | Home Page
Alt + Left Arrow | Back one page
Alt + Right Arrow | Forward one page
Ctrl + A | Select All
Ctrl + C | Copy
Ctrl + D | Add Bookmark
Ctrl + Enter | Open a selected link
in a new window
Ctrl + Enter | Complete a .com address
in Address bar/Location Bar
Ctrl + F5 | Reload and override cache
Ctrl + H | Toogle History in sidebar
Ctrl + I | Toogle Bookmarks/Favorites
in sidebar
Ctrl + N | New Window
Ctrl + O | Open File dialog
Ctrl + P | Print
Ctrl + R | Reload
Ctrl + V | Paste
Ctrl + X | Cut
Ctrl + Y | Redo
Ctrl + Z | Undo
Shift + Backspace | Forward one page
Backspace | Back one page
Del | Delete
Down Arrow | Go down one line
End | Go to bottom of page
Home | Go to top of page
PageDown | Go down one screen
PageUp | Go up one screen
Up Arrow | Go up one line
Enter | Open a selected link
Esc | Stop
F1 | Open Help
F5 | Reload
F11 | Toggle Full Screen mode
Firefox/IE common keyboard shortcuts
by functional group
Inter-page Navigation and Control
Alt + Home | Home Page.
Backspace | Back one page
Alt + Left Arrow | Back one page
Shift + Backspace | Forward one page
Alt + Right Arrow | Forward one page
Enter | Open a selected link.
Ctrl + Enter | Open a selected link
in a new window.
F5 | Reload
Ctrl + R | Reload
Ctrl + F5 | Reload and override cache.
Esc | Stop
Intra-page Navigation
Down Arrow | Go down one line.
Up Arrow | Go up one line.
PageDown | Go down one screen.
PageUp | Go up one screen.
End | Go to bottom of page.
Home | Go to top of page.
Editing
Ctrl + A | Select All
Del | Delete
Ctrl + X | Cut
Ctrl + C | Copy
Ctrl + V | Paste
Ctrl + Y | Redo
Ctrl + Z | Undo
Window Control
Alt + F4 | Close Window
Ctrl + N | New Window.
F11 | Toggle Full Screen mode.
Ctrl + Enter | Open a selected link
in a new window.
Miscellaneous
Ctrl + D | Add Bookmark
Ctrl + I | Toogle Bookmarks/Favorites
in sidebar/Explorer Bar
Ctrl + H | Toogle History in sidebar/
Explorer Bar
F1 | Open Help.
Ctrl + O | Open File dialog.
Ctrl + P | Print
Alt + D | Select the Address Bar/
Location Bar
Ctrl + Enter | Complete a .com address
(only in Address bar/Location Bar)
Thanks, Bob! That’s a good reference to have, although many of the items on the list are actually common to just about all Windows apps. I don’t think very many people will want to memorize all these shortcuts, but knowing at least a few can be a real timesaver.
(PS: I edited your comment to remove a typo and so that it would fit without distorting the page layout.)