Yamli editor

The Yamli editor allows you to write in arabic without using an arabic keyboard.

http://www.yamli.com/editor/ar/

Using Yamli is very easy. Simply spell out each Arabic word the way you would pronounce it, and Yamli will convert it to the corresponding Arabic word:

For example, type "3arabi" or "arabi" to enter "عربي"

You can also use common shortcut characters. For example "3" for "ع"" and " "7" for "ح", etc ...