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While at iOS training a few weeks ago one of the instructors mentioned an OSX program called Dash. Dash is an offline documentation viewer, which sounds kinda boring, but I'm incredibly pleased with it.
Dash works by letting you download a doc set (over 130) to your local machine. The range of docs sets is pretty darn impressive, and even includes ColdFusion.
Once you've selected your doc sets, you know have access to them offline, which admittedly is probably not something you will have to worry about often, but what I love about this app is how quickly you can get to what you need - even when your online. Some of my favorite platforms don't necessarily have the quickest, simplest docs to browse and Dash just fixes that problem.
Dash also has great integration with other apps:
Of particular note is the Alfred integration. I can now fire up Alfred and search Dash directly, which is really freaking cool. Since Terminal access exists I'll also be able to build a Brackets plugin for Dash too.
The only issue I ran into is that sometimes the categories Dash uses (classes, functions, etc) don't necessarily map to the content in question. jQuery Mobile is a great example of this. It places the UI stuff (the widgets) under a Classes category which isn't exactly appropriate. But that's a minor quibble.
Dash can be downloaded for free, but it will nag you to purchase the commercial version. At 19.99, this was an easy purchase, but even the nagging was pretty minimal.