No Format is a plugin to prevent wordpress from applying any formatting to your posts. I got tired of wordpress formatting my carefully crafted HTML and messing up my posts, so I created this incredibly simple plugin to prevent it. It disables two of the filters wordpress passes your post through before displaying it. If you're posting using the code editor (as I am), these filters can really wreak some havoc on your code.
You can download the plugin here. To install, just unzip and copy to your plugins directory, then activate in the admin.