CTRL-F12 lets you quickly view a unit in your project.
Note that the above will open a seletion box of unit's "open" within the project space. If you want to open a unit that has been included in the unit you are currently viewing (without having to hunt it down on your harddrive), simply move the cursor to the first character of the filename and press CTRL-ENTER. (actually the cursor can be anywhere within the filename and it will work).