In Windows XP if you click Start, Run (or Windows-key + R) you get a little dialog for running things directly. If you start typing, a resizable scroll-list pops up underneath the edit-box.
I want something similar, so when a user is typing in a name to an edit-box, a list will suddenly appear if suggestions can be made. But I don't know if I need to write it all myself, or can use some existing controls/code from somewhere.