Mr. moving entirely to Ubuntu is building a resource pack for Construct? Aww.
I'm already doing a lot with my own projects but I'll contribute a few things. I don't know what styles would be wanted (probably all) but here's an example of some of mine:
<img src="http://i19.photobucket.com/albums/b161/buddy40/Trees.png">
Did them very quickly, but it should give somewhat of an idea of my style(s).
(Edit: Doesn't have to be small either, can do large sprites as well.)