Good question! for me, it depends mostly on the source of the stress... if i am at work - a short walk or quick chat with a friend (or a short walk AND a quick chat with a friend - at starbucks!).
At home if i am frustrated or stressed i tend to bake. I like the nearly instant gratification of creating something out of almost nothing. And it's tasty! Normally I dont even care about the finished product, it is more about starting and completing something.
A movie and/or TV watching, reading a real book, or writing in a notebook with an actual pen (as opposed to computers for any of those things) help relax the 'computer' part of my brain and really engage rusty areas that are longing for some attention. it's like i can actually feel my brain saying THANK YOU! and it's nice
finding time to destress, however, is the tricky part!!