Back in December of 2011, Google changed the way screenshots were handled in the Play Store. Where they used to open in their beautiful, hi-res glory, they have since opened as a tiny version of themselves. It's annoying, especially for tablet screenshots. To circumvent this, you could open the image in a new tab and append h=2000 to the end of the URL, which forced the screenshot to open in its full-size.
The Play Store's web market has come quite a long way since it was first announced back in February of 2011. Still, that doesn't mean it's perfect - among others, there are quite a few filter options still on the request list. For example, many users want to separate their free and paid apps in the My Apps interface. Thanks to a Greasemonkey script Artem just stumbled across, now you can.