Coda is awesome. I just used it to toss up a quick website (www.snowkitemasters.com) and it simplifies the workflow a ton... I'm buying it for sure. Definitely download it and try the 14 day trial out. And be sure and read the help, it has some really killer features that are somewhat hidden.

CSS Edit is also indispensable if you work with CSS on a mac. The XRay and override feature is brilliant.It allows you to open any website in the built in browser, mouse over to see the DOM structure, and then you can edit the style sheets and see live updates. It's awesome to see how a site that you like did a specific layout.

And as a sidenote... it really seems like there is an underground changeover going on to the mac platform. I have at LEAST 10 friends who have always been windows only that have bought macs in the past MONTH. Maybe it's not so underground, but it feels like macs are finally starting to mainstream.