TeamViewer is an app that lets you connect to other Macs and PCs via the Internet to share desktops, transfer files, walk through presentations, and control other computers remotely. It's even free for noncommercial use, making it a great choice for your pro bono troubleshooting for friends and family, or for just accessing your own Mac from the road.
The interface is simple: you just open TeamViewer and you're prompted to either create a session or wait for one. A unique ID and password is created for each session, and you need TeamViewer on both computers (if you're helping someone, they can just download and run the small "TeamViewer QuickSupport module," so they don't even have to install the full app). Once a session is running, you can see the other computer's desktop on an inset window. Your level of control depends on the parameters you set for the session (Remote Support, Presentation, or File Transfer), and the interface and menus are straightforward, with intuitive touches like a big "X" that either user can click to end the session.
In the latest update to TeamViewer, you now have the ability to create meetings with up to 25 participants. You can now schedule meetings in advance within the app, perform a practice run before the big day, and then hold a meeting complete with video and other media -- on all your devices. In our test runs, we were able to get a meeting up and running and use many of the new features. We think TeamViewer users will appreciate the new meeting features because they're intuitive and don't require a lot of practice to create a meeting on-the-fly.
TeamViewer isn't perfect -- for example, it often feels less like a Mac app and more like a ported PC program, which it is -- but it's surprisingly stable, fast, and (perhaps most importantly) free for personal use. With extras like integrated chat, heavy-duty encryption, and new meetings support with tons of features, TeamViewer is definitely worth a download for anyone who needs this kind of functionality.