Link : https://itunes.apple.com/us/app/screenfloat/id414528154?mt=12&uo=4&at=11l5Lz
Screenfloat is currently on sale today. If you’re unfamiliar with the app, it allows you to grab any portion of your screen as a screenshot and have that float above every other window.
This is great if you just want to consult something without the need of command+tabbing back and forth and also great to quickly capture and share screenshots.
Another great app by the same developer is Yoink. While not currently on sale it’s a worthwhile purchase nonetheless. Screenfloat, for lack of a better definition: is a conjunction of Yoink and Screengrab.