The other day, I wanted to use FrontRow (the multimedia application included on most new Macs now) to play some videos, but couldn't find my Apple remote. Unfortunately for me, using FrontRow without the Apple remote isn't really well documented. Fortunately for you, I figured out how it works. Below are some important keystrokes to use when you are in this same situation:

Command+Esc : Activates FrontRow
Esc : Goes back one level; Exits FrontRow
Left Arrow : Rotates menu counter-clockwise
Right Arrow : Rotates menu clockwise
Up Arrow : Scrolls up
Down Arrow : Scrolls down
Enter : Selects an item

Below is a short video sample of opening and exiting FrontRow without an Apple remote: