This list of Lifehacker readers’ most recommended free apps contains some real gems, including some of my favourites (Google Chrome, Dropbox, uTorrent, Gmail, Winamp etc.)
MozBackup is a free utility for backing up your Mozilla, Firefox and Thunderbird profiles. Mozilla haven’t yet released an official backup tool, and while it’s possible to achieve the same effect by manually copying folders, MozBackup makes the process much simpler.
Alex Feinman’s ISO Recorder allows you to burn CD/DVD ISO images under Windows XP/2003/Vista without the need for a dedicated CD burning application. Lucersoft’s LC ISO Creator enables you to do the process in reverse, i.e. create an ISO image from a physical CD/DVD.
Edit: Alex’s ISO Recorder now supports image creation, removing the need for an external tool such as LC ISO Creator.