Working on CosmWiki today I hit up a huge problem... making changes to the .module file had no effect. I spent a couple of hours poring through documentation looking for some way to "clear the cache". Lo and behold, and I feel like an idiot, but do to Drupal's module loading system, for some reason it was latching onto one of the copies in my _darcs source control directory. So I re-initted up in the main drupal directory and problem solved. Now I just feel like an idiot for not trying that sooner.