Well, it's actually 2 computer favorites.
They're both really simple programs that I've used for a long, long time. They are compact, simple, and compatible with just about any type of document. And, they are both incredibly powerful and free programs. Yay!
The first one is Ifran View.
It's basically a picture viewer, which probably doesn't sound too necessary or exciting. But it makes taking screenshots a breeze, it does batch photo converting, and it's very easily customizable to do anything you'd like with your photos. I just don't think it works on a mac quite yet :( It is much better than Grabber.
The second one is VLC VideoLan video player.
It can play almost any type of video file, rip dvds, take images from videos, and convert video files to just about any file extension. I love this program so much. It's also the only free way I've found to put the oodles and oodles of DVDs that I've already bought and own onto my ipod. And this one is mac-compatible!