There is a great little discussion going on atthis blog, about the 10 greatest Mac OS X applications. They suggested:
QuickSilver, a launcher on steroids.
Ecto, still the best blogging client in the world and well worth the $18 dollar price.
NetNewsWire – a lot of pretenders out there, but when it comes to Apple like intuitiveness, this is my choice for a RSS news reader. You can get a freeware version as well.
VideoLan/VLC – the cross platform media player that is better at handling video files better than any other player. Of course the price is right.
BluePhoneElite, the perfect application to help you get the most of your bluetooth enabled phones. SMS, caller ID and a iTunes pause function, make it the most used application on my PowerBook.
Cocktail, a general purpose utility for Mac OS X. The application serves up a scrumptious mix of maintenance tools and interface tweaks, all accessible via a gorgeous graphical interface and toolset. Definitely a must have for us non-UNIX geeks.
CandyBar, the perfect way to spend your weekend, when all your friends are off doing ungodly activities like climbing mountains, biking or simply running. This is the perfect tool for pimping your Mac.
USB Overdrive X – turbocharge your multibutton mice for optimum productivity.
FolderShare – The simplest way to keep your folders synchronized between various Macs and even PCs. There is a free version as well.
Camino – Even as a beta product, it is still feels better than Firefox and better than Safari!