Windows only: Free file browser Q-Dir makes for a good USB drive app or installed replacement for Windows Explorer for those who do a serious amount of file swapping, or just like to be able to keep multiple folder views open at once. The app—which installs by default, but can run by itself after renaming it "Q-Dir.exe"—offers a customisable number of panes, though the default four-square is a pretty good starting point. You can save any view you like to a favourite button, along with adding shortcuts to frequently-accessed folders. There's also a quick-filter box in the lower-right for easy sorting and finding, and if you use Q-Dir regularly, you'll be glad it keeps your right-click shell extensions and offers its own "*Q-Dir" launch option on right-clicking a folder. Q-Dir is a free download for Windows systems only.