tl;dr: Want an interesting Dart project? Port Pop, Pop, Win! to StageXL. If you do a good job, you're code will get into the Dart SDK.
When I wrote Pop, Pop, Win! I hacked together an HTML Canvas graphics library into bot_web. The library – bot_retained – did everything I needed, but I really haven't done much with it in over a year.
In the mean time, StageXL has been going nuts. It supports rendering to Canvas and WebGL. It supports Texture Packer. Bernhard has been keeping it fresh.
I'm actively trying to cleanup a bunch of little projects I've built over the last couple of years. Deprecating my own retained graphics library and moving folks towards StageXL seems like goodness.
Interested in doing the port?
The source code for PPW now lives in the Dart SDK. I'd suggest doing a copy-paste of the project into a new Git repository and starting there. The graphics bits are pretty well isolated. If you're pretty serious and can show that you've made a stab, I'm happy to offer help.
Dig in. Send me a link to your project on GitHub if you make progress or hit any bumps.