The core of my profession is industrial design, but I've had the opportunity to implement a diverse skillset on a variety of projects, both as a corporate designer and as a consultant.
Graphics & branding: because sometimes a little logo goes a long way.
3-D modelling & rendering: because if 3-D printing is 'the future' then knowing how to manipulate 3-D data will be useful.
Video production & photography: because 30 seconds of video + cool music is better than a 30 page PowerPoint.
Sketching & ideation: because real creativity shouldn't require a power outlet.
Research & observation: because absorption & synthesis should be a 24-7 thing.
Writing & storytelling: because at some point you'll have to describe what you do, and eloquence is...really...good.