Here's the very first (probably buggy) version. Expect oddities like buttons disabling or being enabled at inappropriate times, since I've not thoroughly tested any of it. I'll enhance it and fix it up later - it's not really suitable for anything except a quick look around the interface, although it can save and load animations.

Future enhancements include:

* resizing anchors for the selections
* better preview controls (timeline, forward/back, etc.)
* fix any outstanding bugs
* file history
* anything else I can think of
* make the web page nicer!

The idea is that you load a tileset (e.g. one from here). You then add invididual rectangular selections for individual pictures within the tileset. You can create sequences for animation - each sequence has frames, which can be displayed in order. Clear as mud, no?