The Pochmann cube is a sticker pattern designed by Stefan Pochmann. One of the key elements of the sticker pattern is the way that the centres are marked to show orientation. This creates what is sometimes referred to as a super cube. In addition to solving the faces in the usual way, you have to ensure that all of the centres are correctly oriented - something you don't have to do with a standard 3x3x3.
There are several things about the Pochmann cube that make it an interesting item to make or have. The first is Stefan Pochmann himself. His site is excellent - full of interesting material. He holds and has held lots of records for all sorts of puzzles, is an excellent programmer and creator of many solutions and approaches to solving puzzles that are still in use today. The need to rotate centres is the main feature of the cube that I like. The shape-changing puzzles often need this and, with the shape variations, it can be hard to get used to. It's easier to see what you are doing on a cube and then translate that to the shape-changing puzzle. My cube is not a speed cube so I have to turn it slowly - so I get to watch what I'm doing. The extra colours match the colours adjacent faces and you see the effect of algorithms pretty well. It's also useful for spotting cases for various stages of a 3x3x3 solve. The extra colours mean that you can tell cubies apart by looking at only the cubie. I often find myself reaching for this when trying out new algorithms for dealing with twisted pieces on things like the mastermorphix.
There are a few cubes for sale with these stickers although I haven't seen anywhere that sells just the stickers by themselves.