ReText is a simple but powerful text editor for Markdown and reStructuredText. It is written in Python using QT Libraries, with that said you need to have QT installed in your system in order to run ReText (Description copy pasted from ReText website, I’m lazy I know :D). I’ve been using it previously on my Ubuntu system with GNOME desktop without problem at all, however when I installed and run it on my Linux Mint LXDE 12 system, the toolbar icons is missing and not displayed at all, only texts are displayed as you can see on the screenshot below.
Markdown is a pretty neat alternatives if you are bored with the default WYSIWYG editor that wordpress has to offer, of course you could always use another 3rd-party WYSIWYG editor available for wordpress such as TinyMCE. But if you want something simple and neat, try markdown instead.