PinMy.co

I use PinMy on my desktop and mobile for gathering feedback from my design clients, and the browser extension gives me the ability to snap screenshots and add them directly into my folders (and then start Pinning for client feedback) without needing to slow down my workflow. The extension will hopefully see some added features, but for basic screenshotting, it gets the job done and that added integration keeps my workflow smooth, quick, and easy.