In the spirit of the Expressions Lab, here are a series of mostly unrelated topics, each showcasing an interesting and hopefully useful idea or technique. Unlike the Expressions Lab, you will find a more detailed analysis of the code here.
The code itself appears twice. The first version is for your convenient copy-and-paste use. You should be able to drop these expressions right into your own AE projects. The second version is annotated with my comments to help you understand how the code works.