AmazonBasics Metal Monitor Stand
Having your monitor at the right height is essential for proper ergonomics. There are a host of laptop stands (such as the Rain Design mStand), but you don't hear much about stands for external monitors.
I found a great option from the AmazonBasics brand. For only $19.99, you can pickup a silver or a black model. It raises your monitor up over 4" and can hold up to 40 pounds. I like how it has room under it for things like my keys or coffee cup.
Get it on Amazon for $20.