OS X Tip: Snagit
Disclaimer: Other than being a consumer, I am not affiliated with any of the products I mention in this post.
If you use OS X and have a need to create screenshots or screen recordings then I personally recommend Snagit (works on Windows as well) by TechSmith. Snagit provides you with a little nub that sits on the edge of your screen wherever you decide to place it.
Clicking the big red button will begin a screenshot or screen recording depending on which you have selected. You can also start snagit in either mode via global keyboard shortcuts. Snagit allows you to edit your image after you take a screenshot and offers a litany of sharing options to your favorite services (except imgur, which is kind of annoying).
If you use TechSmith's Camtasia Studio you can easily import video captures from Snagit into Camtasia and edit them with ease. Camtasia even lets you create animated gifs out of them. (I used Photoshop CC to create the animated gif you see here. I could have easily done it in Camtasia Studio if I owned a copy, but I work for Adobe and have a free Creative Cloud membership so I never renewed)
Snagit is $49.95 at the time of this post and it is well worth the price in my opinion.
TechSmith recently released a version of Snagit for Chrome as well but I don't yet recommend it over other image capturing Chrome extensions because it's very bare bones at the moment. I'm sure TechSmith will expand it as time goes on.