During my days on the Genius Bar, one common problem that I'd often see was damaged headphone ports on the Mac. Whether it was due to the mini-jack snapping inside the port (leaving part of it stuck) or the output was stuck on digital out, what seemed to be a relatively minor fault would often end up being quite costly.
I use my MacBook Air on a desk with an external display, keyboard, trackball, and set of speakers. Since I often travel with my MacBook Air as well, I'm constantly plugging and unplugging the speaker's mini-jack, something that would fill me with dread.
The solution? A £2 USB sound card that requires no drivers, using OS X's built-in audio device support. I keep this plugged in to my USB hub with the speaker attached. As soon as I put the Mac on my desk, all I connect is my display and USB cable and the audio automatically switches to the USB sound card, thus avoiding cable fatigue and any potential damage to the headphone port.
There are USB or Bluetooth speakers out there that negate the need to use the headphone port, but they're few and far between. I've also found Bluetooth audio to be pretty lousy in OS X.