You should try FluffyApp. Captures any part of your screen you want on the fly and uploads it to their server on the spot and gives you a short url in your clipboard. It's the thing I can't live without!
I've been using FluffyApp for quite a while. It storages the screenshots on the cloudapp service. For taking a screenshot of a region of the screen just press ctrl+shitf+print_screen.
I've got a CloudApp account so I use CloudApp on Mac and FluffyApp on Windows. Fantastic programs, both have fast, capture and drag captures. Also with a tiny memory footprint.
Also for some shameless self-promotion I also helped dev a program called SnagIMG which is similar to SwiftKit's screenshot manager, just without the SwiftKit so you can use it anywhere.