A small and useful paper stand, allowing your document to stand upright while you read it. 

The stand takes almost zero desk space, both when empty and when holding a piece of paper. It can hold an A4 or letter size paper, in the portrait orientation.

Update: I added a variant with the top surface parallel to the desk surface. This avoids visible jagged layer lines at the top, at the cost of not being parallel with the paper's edge. It's available at Vertical paper stand - Flat top version.

Possible uses

• Holding sheet music upright, on a desk, table, or on a music holder that is too low. 
• Holding up reference documents next to your computer
• Easy transcribing of notes and documents
• Keeping multiple important documents visible on limited desk space
• A cool-looking display for awards
• Explaining intrinsic surface curvature, an interesting phenomenon in mathematics and physics

How it works

This tool uses the concept of Gaussian curvature - a sheet of paper can bend in only one of the two main directions, but not in both. By slightly bending it horizontally, it prevents the paper from bending vertically and falling over. The phenomenon is also explained in The Remarkable Way We Eat Pizza.