Mac: One of the lesser known features in Yosemite is a new Dictation Command option in Automator. As MacWorld points out, this means you can set up a command to launch any Automator action you want, including launching apps and ejecting disks.
First, you'll need to create an Automator workflow using the Dictation Command function. Type in the command you want to say, create your workflow, and then you'll be able to launch that workflow by loading up the dictation HUD (Tap the Fn key twice by default). It's pretty easy to set up, so head over to MacWorld for the full guide.