One of the most baffling gaps in Mac third-party software is programming-oriented text editors with autocomplete. Now, obviously there’s XCode, vim, and emacs (which, being free, are all something of a problem for would-be competitors), and a bunch of cross-platform tools like Eclipse and Komodo, but XCode is really oriented towards Cocoa development and is kind of like using Microsoft Word to edit a shopping list, while the others are all non-Mac-like (and kind of suck anyway).
The Mac heavyweight text-editing champs — BBEdit and TextMate — have many great features, but don’t do autocompletion very well or at all, respectively. (There’s some kind of third-party hack add on for TextMate, but you need to compile it yourself and few seem to be able to get it working.) A lot of Unity developers were using PCs or Virtual Windows boxes to run Visual Studio just because it has an autocompleting text editor that doesn’t suck — that’s how bad it was. (Now that Unity runs on Windows their lives have gotten much easier, which is a pretty sad statement.)
Before you scream at me about how, say, Subethaedit has some kind of autocomplete support, or mention Coda (which has OK autocomplete support) or Espresso (which may one day have halfway decent extensible autocomplete support but right now is a work-in-progress), go and try Visual Studio or, if you’re allergic to Windows how about Realbasic. Realbasic‘s built-in text editor has autocomplete that doesn’t suck, e.g. it recognizes context, knows about intrinsic language constructs as well as library functions and the stuff you’ve declared, and doesn’t incorrectly complete stuff you need to fix constantly or fail to offer “function” when I type in “fun” in a .js file.
I will say this: TextMate’s macro facility is truly awesome (you can type swi->TAB and get a switch statement template, and then tab through the bits you need to change, almost like a context-sensitive-in-place-dialog-box), if this were paired with a proper autocomplete system (like RealBasic’s) it would be the best I’ve seen and then some — maybe 2.0 will have this — but right now the situation on the Mac remains pretty dismal.