Windows only: If you're serious about keeping your workspace portable, previously mentioned tools like the Portable Apps Suite or MojoPac are the go-to resources for Windows users. However, if your thumb drive is already scrimping for space, and you just want a few super-lightweight apps that can handle most general office tasks, from word processing and spreadsheets to email and file sharing, the Tiny USB Office might be for you. Weighing in at under 2.5 megabytes, this lightweight suite of office apps is a no-brainer to throw on any old USB stick for a little productivity on the go. Tiny USB Office is freeware, Windows only.