Mac/Linux: Wine has long been the best free, open source tool for running Windows apps on Mac and Linux. Yesterday it finally hit version 2.0, bringing along support for Microsoft Office 2013 and 64-bit software on Mac.
Aside from the new support for 64-bit software and Office, the update also brings along improved font handling, better drag-and-drop support and support for a bunch of new graphics cards. As always, Wine is still very much a work in progress, but the newest release marks some big strides in what software it can support. You'll find a full list of all the improvements and new features over at the Wine site.