Submit portable freeware that you find here. It helps if you include information like description, extraction instruction, Unicode support, whether it writes to the registry, and so on.
Diskitude helps you figure out what is taking up space on your hard drive. Its intuitive and animated interface allows you to easily explore your file system and prune your files.
Finally a successor to Overdisk (it hasn't been updated in a while). I don't know why more apps don't use the concentric circles layout, it's much easier to visualise and navigate.
Old topic update: Diskitude has a new release dated 2013-04-12, which doesn't seem to work on Windows XP anymore (also, it still doesn't have an icon).