Firefox shortcut keys to switch between tabs

I just tried this under Snow Leopard and it worked beautifully:

1. Open System Preferences => Keyboard
2. Go to Keyboard Shortcuts
3. Click on "Application Shortcuts" on the left
4. Click the little "+" to add a program
5. Navigate to Terminal (it's hidden in Applications/Utilities)
6. For the Menu Title type "Show Next Tab" or "Show Previous Tab" ("Select Next Tab" and "Select Previous Tab" for Mavericks or older) (Also, these items will be different for languages other than English.)
7. For the Keyboard Shortcut type Ctrl-Tab or Ctrl-Shift-Tab
8. Click Add. You are g2g!

Firefox 19 and later now support these shortcuts natively:

Firefox 19 added shortcuts to move tabs:

• Ctrl+Shift+PgUp to move left, and
• Ctrl+Shift+PgDn to move right.

The change is recorded as bug #364845; here is the specific commit that added the shortcuts.

Therefore, the Move Tabs extension is no longer required; in fact, if you have it installed you should disable it (or else the shortcut will move the tab twice).

For moving tabs to a new window, the Tab Mix Plus extension provides the shortcut Ctrl+Alt+N (this can be customized in the extension's options). For moving the tab into a different window, there's no default shortcut, but you can set it up by changing the merge behavior (Tab Mix Plus Options > Events > Tab Merging) to merge only the current and last-focused windows, and then setting a shortcut for Merge (the default shortcut Ctrl-Shift-M conflicts with a built-in one).