Computers and smartphones can store and sift through reams of data. With a bit of help, you can harness that power to manage the information you need, whether it's something hidden away in an obscure email message, a search engine result, or a tidbit that you haven't written down at all. The nine services and applications below can help you become more productive and make better use of the technology you already own. Each offers a free version, too. Thanks to these knowledge managers, your next project may be easier to finish than you might think.
(For links to all of these downloads and services in one convenient list, see the "Your Personal Wikipedia" collection.)
One popular type of knowledge-management service is the "catch-all" service, which acts as a big bin into which you throw random bits of knowledge for retrieval when you need the information.
Evernote is probably the best-known service in this category. It has a desktop application, a Web app, and mobile apps that allow you to feed new information and search for existing data. Evernote also offers the Trunk, a hodgepodge of third-party applications, services, and hardware that all play well with the service.
Another attractive catch-all system is Springpad. Though it doesn't have a desktop application, it does provide a slick Web-based interface, as well as browser add-ons and mobile apps. What makes Springpad special is context: If you clip a Web page containing a recipe, for instance, Springpad recognizes it as a recipe, parses the ingredient list, and even offers to put the ingredients on your shopping list.
While Evernote has a limited free version, Springpad is entirely free, and displays occasional promotional messages based on the information you save into the service.
Browser-Based Wiki Systems
Just as Google is synonymous with "search," Wikipedia is synonymous with "knowledge." This global online encyclopedia proves that the wiki format works well for managing knowledge. You can make a wiki of your own, too. Of course, your wiki doesn't have to be all-encompassing; it can focus on one particular topic or project, or serve as an interactive journal.
On Wikispaces, you'll find a simple way to get started with a collaborative wiki. With this online service, you can quickly set up your own public wiki, pick a theme, tweak the settings, and invite collaborators. The free plan includes up to 2GB of data, more than enough for most projects. You can't make a free wiki private--which means anyone can read your wiki--but only the collaborators you invite can edit it.
Not all wikis must be collaborative--or even public, for that matter. TiddlyWiki is a tiny personal wiki that resides in a single HTML document, with a small, optional Java applet on the side. TiddlyWiki costs nothing, can live in a Dropbox folder or on a USB stick, and works with pretty much any modern browser. It's customizable, as well, and it even has optional plug-ins. Your wiki is divided into individual topics called "tiddlers," which are ideal for storing tidbits of knowledge.
Desktop-Based Wiki Applications
Wikis aren't limited to the Web, either. Desktop wikis are full-fledged applications that offer easy-to-use text formatting and quick linking, but can be fast and nimble, not to mention private.
One well-known personal wiki is Tomboy, from the open-source GNOME project. Tomboy does everything it can to stay out of your way and just let you write: It automatically saves notes, and it makes links to existing topics magically appear. If only its installation routine were as magical--on Windows, Tomboy requires you to install the GTK# runtime before you can use it. On the plus side, it works on Linux (the OS it was meant for), as well as on Mac OS X. And Tomboy is unique in that each note resides in its own window.
A more conventional-looking wiki, Zim is also cross-platform (Windows and Linux), but it uses a single-document interface with a topic tree on the side. Although it is easier to install than Tomboy, it doesn't always offer instant results: Sometimes you need to reload the page before links start working.
Like Zim, WikidPad uses a single-document interface with a topic tree, but it has a native Windows look and feel, and it can serve as a portable app.
Tomboy, Zim, and WikidPad are all free and open-source.
If you are looking for a commercial desktop wiki, ConnectedText is a good choice. This powerful personal wiki starts at $40, but is a mature product with support for revisions, outlines, tables, and more.
Roll Your Own Wiki
Last, but certainly not least, is the geekiest option. MoinMoin is a Python-based open-source wiki for those intrepid users who enjoy installing server-grade software, fiddling with text config files, and watching log lines fly past in a console window.
Employed in large collaborative wikis such as the official Python wiki and the Debian wiki, MoinMoin is surprisingly easy to install as a single-user desktop wiki. If you already have Python, basically you just have to extract it and run a single Python script to start saving pages. Configuring MoinMoin is a different matter, though.
Deciding which knowledge management system to use is all about personal preference. You may find one you love at first sight, or you might encounter a system that gradually grows on you until you wonder how you ever lived without it. Regardless, having a solid personal database can save you tons of time and frustration.