Does what is says on the tin. You can assign a fixed set of operations to each corner of your screen, or you can even choose a program to be run on that action. The slight annoyance for me is that this latter feature is limited to ".EXE" files. The reason I wanted Hot Corners was to imitate Expose, by assigning Windows Vista "Switch Windows" command to the right corner (which is a shortcut, not an .EXE). Will be sure to check out future versions.