IME : Warcraft Input Method Editor
IME is, well, an IME. If you've ever used one, you'd know the level of simplicity if brings to type in other languages or keymaps.
IME is an attempt to simplify all that, and allow using characters outside the normal range to type in WoW. Normally, using the two locales I've found (Greek and Cyrillic), typing them via a Windows IME has failed, bringing up only question marks. Using an addon, however, they can be inputted easily.
With IME loaded, you'll have a box. A small box. A small blue box. The small blue box will probably say "N/A" - this is the default IME. It changes nothing. Click it, however, and you change to a new keymap. Type in your chatframe and the characters will be changed automatically.
Pressing Ctrl + Tab while typing will also cycle through available input methods.
Included are keymaps for adapted Greek and Cyrillic, both phonetic, and a leet layout.