
Luminotes is a terrific Web-based personal wiki that helps you collect and organize information. It's great for project planning, book writing, or as an in-basket for random data you want to hang on to. It doesn't require any special markup skills so Luminotes is a great collaboration tool for people with all levels of computer experience. For solo use or for working offline, there's a desktop version that runs on Linux and Windows.
Licensed under the GNU/GPL, Luminotes has always been free as in speech but now it's also free as in beer. Dan Helfman, the project's creator, says dealing with recently implemented U.S. sales tax laws is too much of headache so he's decided to eliminate monthly subscription fees and charges altogether. The desktop version and online service will continue to be supported for the foreseeable future.
If you want a notebooking application that's dead-simple to use, yet more robust than a simple note-taking app, have a look at why Luminotes personal wiki might be just the ticket.