Resizing oversize window

• Enable JavaScript. (Firefox: Tools -> Options -> Content -> Enable JavaScript; Mozilla Suite: Edit -> Preferences -> Advanced -> Scripts & Plug-ins -> Enable JavaScript for -> Navigator)
• Make sure scripts can resize windows. (Firefox: Tools -> Options -> Content -> Advanced JavaScript settings. Mozilla Suite: Edit -> Preferences -> Advanced -> Scripts & Plug-ins).
• Type: javascript:top.resizeTo(800,600) into the Location Bar and press Enter.

Note: If your screen resolution is 1024 X 768 then instead of the above, type: javascript:top.resizeTo(1024,768)

Using the appropriate numbers inside the parentheses, separated by a comma, will reset the browser window to (almost) full screen.

You can also make a bookmarklet* and place it on the Bookmarks Toolbar, so you don't have to type it more than once. (*bookmarks that contain JavaScript content are called bookmarklets)