Windows: If you're thinking about moving to Windows 7 but dreading the migration, Windows 7 Migration Tool takes some of the hassle out of the process.
Windows 7 Migration Tool comes in several flavours including a free basic edition. The free edition will check for compatibility issues, scan your XP installation for applications and save application settings as well as generate a list of applications you need to download — the basic edition doesn't automate the reinstall process for you unfortunately. It also transfers your desktop personalisations and the contents of My Documents.
Windows 7 Migration Tool Basic Edition is freeware, Windows only. Know of a tool for easy migration to Windows 7? Let's hear about it in the comments.