Tabkeys lets you assign custom keyboard shortcuts for common tab actions in Safari. Available actions are: opening a new tab, closing the active tab, reloading the active tab, switching to the next or previous tab, and moving the current tab left or right on the tab bar.
For each action, you can assign up to three characters as shortcuts, alone or in combination with Command, Option, and/or Shift. For example, you could assign lowercase "w", uppercase "W", and ç (Option+C) to Close Tab.
You can also define any number of web addresses, including bookmarklets, and assign a hotkey to each. Each address can be set to open in a new tab or the current tab.
