Eternal Storms Software's ScreenFloat for Mac OS X (10.7 and higher) is a screenshot utility with a twist. It lets you create screenshots that float above all other windows. This means you don't have to resize or move windows around just to keep a screenshot visible.
This isn't something I need to do often, but if you deal with lots of screenshots, you'll find that ScreenFloat does its job well. Customizable and easy to use, it always keeps information visible.
To make the creation of floating shots for text easier, ScreenFloat implements a system service that works with all Cocoa applications' selected text. You can create a floating shot with the utility either via the menu bar icon or the hotkey. By default it's Command-Shift-2, although you can change this as you wish.
ScreenFloat includes a Shots Browser to categorize and organize screenshots taken with the app. This makes it easy to manage all your screenshots. In the Shots Browser, closed shots are collected, tagged, titled, and organized in collections or smart collections. Collections are folders that you can manually add created shots to. Smart Collections contain shots based on criteria the user specifies.
As I said, sometimes information can’t be copied and pasted easily and a screenshot may be the best way to keep such info handy. With OS X's default screen capture utility, Grab, you have to jump back and forth between the main app you’re using and the screenshot you just took. ScreenFloat eliminates this hassle. Plus, if you need to collate information from multiple screens, Eternal Storms' reasonably priced app handles the task with aplomb.