If you don't need lots of features, I'd recommend DevonNote, the cheapest (currently free on MacHeist, I read the other day) of Devon's various info organizers. I used it for a couple of years until I got Scrivener, which is an amazing info organizing and writing app that's currently winning raves everywhere from MacWorld to the New York Times, but it may be more than you need. I've heard of others like EagleFiler (which unlike many of the others doesn't have to import the files into its own format) and Yojimbo but haven't tried them. Let us know what you wind up getting.