BindingsReminder
Simple mod that shows you a keyboard layout with buttons that have some sort of action associated with them highlighted.
WoWInterface
BindPad
Lets you bind spells, macros and items to key bindings without using action buttons.
Config: /bindpad or /bp
WoWInterface, Curse
KeyBindingSearch
A simple addon that lets you sort through all those dozens of key bindings to get to the ones you want quickly. Just open up your key binding frame and use the search and incremental selections at the bottom.
WoWInterface
KeyProfiler2
KeyProfiler was made to save the key bindings that you are using at the moment so that you can load them later. This means that you can have different key binding sets (PvP, raids, fishing, special raid encounters, ...) that you can switch around with your favorite LDB addon (standard is a minimap button).
WoWInterface
mBindings
Allows you to easily keybind abilities from your spellbook and macros from your macro frame.
Mouseover an ability/macro and press a key to bind them together.
WoWInterface