Is there an extension of some sort that can access the data embedded as the ID3 tags for MP3 files and the like? So for example, I could somehow set an active picture (or similar) to display album artwork?
I've worked a little with this in C#. It's actually quite simple and you might be able to make something yourself. If you drag an MP3 file with ID3 version 1 tags in it into notepad, you will see that in the end the info is located. It's very easy with version 1 because it can only be 128 bytes long (i think) meaning that the tag always starts at the same place relative to the end of the file.
It's a bit more tricky with version2 because the positions of the tags can vary. One difference though is that this info is located in the start of the MP3.
But basically what I'm saying is that ID3 tags aren't encrypted or anything.
As said already, you might be able to do this with the Binary extension.