I had a conversation recently with someone just finishing a master's degree about directions he could take with his career (somehow I've begun to be an elder statesman dispensing advice to the young, though it feels like I just got out of school myself -- and actually I'm still in school). He asked me about what, if any, connections I saw between music (which has been a huge though now less time-consuming part of my life) and doing software and usability design.
I think the similarities are profound and on many levels, especially when it comes to the aspect of collaborating with other people to produce an artifact like a website, application, or song. Many people are involved, with different personalities, skills, approaches, and aesthetics; you have to rely on them because it can't be done alone. Your collaboration and communication can be intense, full of inside references and unspoken things. Sometimes this is frustrating; sometimes it's transcendent. Emotions, egos, intellects, personality quirks, and personal histories come in and out of play. Virtuosity and style are central, and you depend on them (or wish you or others were displaying more). Little things matter. The more you have a sense for what the whole should be like, the more you just know when one of those little things either fits or doesn't fit, whether it's a piece of code, a graphical layout, or a drum roll or guitar riff. At its best it's a beautiful thing and the sum of all of you working or playing together is far more than the sum of the parts.
You can see this unfold in a couple of behind-the-scenes looks at musical collaboration, like the scene in Let It Be where the Beatles are working through arrangements in the studio, and George Harrison is getting criticized over something he's doing on the guitar (I think it's on I've Got a Feeling), and he offers somewhat sullenly, not to play anything at all. Or more amusingly the More Cowbell sketch from Saturday Night Live. You see what someone wants to do, they're expressing themselves, some people like it, some don't, they have to work it out. In this case they come up with some way that it can all fit together.
And there are other times when an individual just doing something him or herself is actually better than doing it collaboratively. One could argue that many singer-songwriters (e.g. Dylan, Greg Brown, Shawn Colvin, etc.) are more powerful and pure when playing completely solo. I only feel this way sometimes (I do enjoy many of their ensemble efforts), but I've also experienced this personally when I've accompanied a friend as a sideman (e.g. Jim Vick, Lowry Hamner). I think they actually sound better on their own. Much more comes through. The collaboration, though perhaps enjoyable to the performers, just adds weight, and noise.
I hope to come back to this thread, it seems so central. Just scratching the surface here.