If you use a Mac, you should be using Quicksilver. I got into Quicksilver as soon as I bought a Mac after reading a post from Merlin Mann over at 43Fodlers regarding Quicksilver.
Most people only use the application launching capability of Quicksilver but if this is all you do, there is so much more that Quicksilver can be used for to make you more productive.
The following video is from Derek Neighbors and is part of some fantastic productivity videos that he produces on Vimeo.
The video shows you how to use Quicksilver to add a calendar entry into Apple iCal.
I hope you agree that this is a neat little video!