I write a lot about the tools that I use. I even named my TInderbox based website "Decision Tools". I write about Tinderbox, the Mac, my iPod and weblogging tools. Besides hardware and software, there are the conceptual tools like Getting Things Done and Decision Theory.
Danny O'Brien has been investigating tools and has drawn some interesting conclusions. Here's a video of his presentation at NotCon. If you'd rather not download the video, some pretty complete notes are here.
One of O'Brien's findings is that people tend to live in one application. I too know someone who lives in Excel. Of course, most of the folks I work with live in Word. Among the "alpha geeks" it's living in a shell is common. These folks work with text files stored on a server because the tools and access are ubiquitous.
While since the advent of OS X I've learned my way around the Unix shell, can use vi in simple ways and have done lots of data analyais with R in Terminal, I still live most comfortably in the Mac OS X interface. I switch actively between Safari, NetNewsWire, Mail, Tinderbox and whatever other programs I'm using for special purposes like image editing or music.
Two of my heavily used keyboard tools are command-space which brings up Quicksilver for opening documents and command-tab which brings up the application switching function of the finder. On my windows machine, I use alt-tab as well. I'd love a Quicksilver-like launcher there as well. Perhaps it's AppRocket, which seems to break Windows rules in order to function.
On the Mac, editing text is more or less the same regardless of what program I'm using. Besides vi in the terminal, I've written in BBEdit, NetNewsWire (now MarsEdit) and TextEdit, but increasing I live in Tinderbox.
Tinderbox is a good candidate for an app to live in since is graphical, so it uses the screen real estate of modern computers. It also works well with text, so information isn't locked up when the software is unavailable or otherwise broken. With all of its options and views, it doesn't feel like working with someone else's tools.
Its drawback is that it's depends on a local database file, so that its locked to a specific piece of hardware. With the long weekend, I've been thinking about how I can create a workflow more integrated around tinderbox. I realized that Tinderbox can function well as the trusted reference system that David Allen advocates in Getting Things Done.