With no information other than the programs, here are the ones I find myself actually using.
No particular order – semi alphabetical. Enjoy!
- [Quicksilver](http://www.blacktree.com/)
- [Chax for iChat](http://www.ksuther.com/chax/)
- [Burn](http://burn-osx.sourceforge.net/)
- [Colloquy](http://colloquy.info/)
- [CoRD](http://cord.sourceforge.net/)
- [CyberDuck](http://cyberduck.ch/)
- [DiskInventoryX](http://www.derlien.com/)
- [DockDrop](http://dockdropx.com/)
- [FrameByFrame](http://web.mac.com/philipp.brendel/Software/FrameByFrame.html)
- [Frozen-Bubble](http://redivi.com/~bob/frozenbubble.html)
- [Genius](http://lifehacker.com/software/featured-mac-download/memorize-anything-with-genius-315064.php)
- [Goban](http://www.sente.ch/software/goban/)
- [Handbrake](http://handbrake.fr/)
- [MacFusion](http://macfusion.makalumedia.com/)
- [Minefield](http://www.beatnikpad.com/archives/2008/06/18/firefox3)
- [Miro](http://www.getmiro.com/)
- [OmniFocus](http://www.omnigroup.com/applications/omnifocus/)
- [OmniGraffle](http://www.omnigroup.com/applications/omnigraffle/)
- [OmniOutliner](http://www.omnigroup.com/applications/omnioutliner/)
- [OpenArena](http://openarena.ws/)
- [Phun](http://phun.cs.umu.se/wiki)
- [Pixelmator](http://www.pixelmator.com/)
- [PogoSticker](http://secretexit.com/games/pogosticker)
- [Pzizz](http://www.pzizz.com/)
- [Quinn](http://simonhaertel.de/)
- [ScreenFlow](http://varasoftware.com/products/screenflow/)
- [SketchUp](http://sketchup.google.com/)
- [Skitch](http://skitch.com/)
- [Skype](http://www.skype.com/welcomeback/)
- [SuperDuper!](http://www.shirt-pocket.com/SuperDuper/SuperDuperDescription.html)
- [Synthesia](http://www.synthesiagame.com/)
- [Tofu](http://amarsagoo.info/tofu/)
- [Parallels](http://www.parallels.com/en/products/desktop/)
- [VirtualBox](http://www.virtualbox.org/)
- [VLC](http://www.videolan.org/vlc/)
- [Perian](http://perian.org/)