It's FREE and the best part of it is that, instead of opening a separate pop-up window to capture the screen, PCPS adds a simple little camera icon to your toolbar. Clicking it allows you to capture a selected part of the screen or the whole page. It's the first program I've found for OS X that works as well and as simply as Screen Catcher (which is fantastic, but doesn't work in OS X). Huzzah!
Here's the proof – all I did was click the camera and create a file name.
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Pearl Crescent Page Saver
(A gazillion thanks to IONCANNON for making my life way easier. Thank you!)