Is there a way to use a keyboard shortcut to quickly paste frequently used addresses without them being on the clipboard? For example, I don't like to stay logged into Facebook, so when I go onto Facebook I usually will need to login. Can I set up a keyboard shortcut that will paste my login info. Obviously I would need to set up several different key combinations for maybe 5 frequently used logons. How can I do this in Mac OS X?
For general typing/hotkey functionality, use Typinator, TypeIt4Me, TextExpander, Butler by Manytricks, or Keyboard Maestro.
You can also use AppleScript and/or Automator to write these simple scripts yourself.
To store web site login information, use your browser's password storage (likely via OS X Keychain, or specific to the browser), or 1Password.
The integrated text substitution in OS X (System Preferences » Language & Text » Text) does not seem to work with browser input fields.