My job requires working at a computer while taking customer calls, but I can usually spare a moment to send myself a lightning-quick email. I tend to get ideas in the car while driving, so my parents bought me a super cool voice recorder that I can turn on with one click without looking and talk the idea out to myself while my left brain and body take care of the autopilot driving bits.

Not ideal for all situations, but a possibility. :D

(Here via metafandom.)