It separates things based on size. Think it’s useful in any other way?

well, here’s another organic molecule, protein.

The word electrophoresis literally means carrying or moving something with or by electricity. It is typically used to analyze the composition of mixtures of one sort or another. Anything that can carry a charge can, in principle, be analyzed by electrophoresis. Usually, you apply an electric field gradient across a solid support (like a gel, or a piece of paper) to drive the charged species through the support medium, which exerts some sort of selection on the different species in the mixture. Size separations based on electrophoresis through gels is a big application. Nucleic acids or proteins can be separated by size, or somtimes by charge, this way. The support medium often is a gel of some kind, with agarose or acrylamide being the most common, but paper and even liquid can be the stationary support phase of the system. Browse something like the book section of Amazon.com for "electrophoresis" and you’ll get some idea about the range of applications. There are lots of them.