See Time Remaining During Video Clip Playback
OS X 10.5's Quick Look has become one of the most-used features of Leopard--at least around my home. It's so nice being able to just press the Space Bar to get a quick glimpse at a file, instead of taking the time to open it in its source application. The Quick Look viewer is a simple tool that doesn't do much more than open and browse documents, though you can use it to zoom in on images and PDFs.
Due to the limited feature set in Quick Look, I was surprised to find that it could do something simple that QuickTime Player, despite its 10-plus year head start, still can't do: display the time remaining in a video clip. QuickTime Player displays the running time of a video clip in the lower left corner, but there's no way that I'm aware of to make that counter show you the time remaining.
Switch back to the Finder, though, and open that same clip in Quick Look by selecting it then pressing the Space Bar. You'll notice the clip's elapsed time appears in the lower right corner of the Quick Look window. To see the time remaining instead, just click on the elapsed time; click it again to toggle it back. Perhaps QuickTime X (coming in Snow Leopard) will offer this useful feature...until then, Quick Look gets the job done.