Well, there's Dreamweaver and Photoshop, and I use MS Word and Excel a lot too. On the Apple side there's Mail, Safari, TextEdit and iTunes. But in terms of the really useful stuff from smaller developers, here's a short list:

NoName Scriptware's Cache Out X
Coding Monkeys' SubEthaEdit (especially for editing .htaccess files)
Dave Nanian's SuperDuper!
Marcel Bresink's TinkerTool
Panic Software's Transmit
And I totally love Ian Page's Mactracker which comes in really handy when buying RAM, HDDs, used Macs, etc.

And I vouch for all of the browsers listed in the page footer!