"Disable wptexturize" is the second plugin I've created for WordPress. To be honest, as far as plugins go, they don't get much simpler than this one. Aside from the header info, it consists of a grand total of three lines of code. Those three lines, though, make a world of difference to someone trying to run a site where formatting is important.
The purpose of this plugin is to stop the wptexturize filter from running on your content, the excerpt for your content (if you use it), and the comments left by your visitors. The texturizer mangles your code by converting what you actually type to what it thinks you mean. For example, the difference between "--" and "–" or straight quotes (what normal people use) and smart quotes (what Microsoft Word uses) is night and day when you're trying to run a command on a *nix system or compile a bit of code.