I've been thinking about making a sprite editor for a while now. Drawing sprites is a big part of what we do when making our games. We have been using GIMP as our primary drawing tool, and while it works pretty well, it doesn't mesh perfectly with our workflow.
So, a few months ago I finally pulled the trigger and started working on PixelMaker. In order to justify making a polished program (instead of a rough-and-ready developer tool), we plan to release it on various platforms - initially on Wii U (the GamePad and stylus are great for drawing) and then later on mobile/PC.
I'm pretty happy with how it is turning out. It loads instantly, unlike programs like Gimp and Photoshop, and is fast and lean - with the features you need for drawing pixel-y stuff, uncluttered by features you don't need (at least *we* think so - we'll see once we have more customers...)
Our initial feature set for release targets drawing individual pixel art pieces, but future planning includes frame-based animation.
On a more dev-centric note, I recently bolted on a project structure interface for us to manage the art assets for a game - designed to integrate with the custom sprite scaling/shadowing/sheet-packing pipeline we currently use:
We plan to get back to working on our already-well-in-progress next game soon, now switching over to using PixelMaker as our core art creation and management tool.
What next game is that? Well, stay tuned for more on that soon!