I was recently stuck on a Chromebook which is pretty much a laptop built around a browser. This meant no Inkscape or Adobe Illustrator for me! I found a fork of Googles SVG edit called MethodDraw:
It lacks a working grid in the current alpha, but just about everything else is there for making quick sprites.
I really prefer the layout to Inkscape for quick doodles.
It exports .PNG and you can save in a very clean SVG format as well. It is very easy to read in a text editor if you decide to animate it later. (Great for webpage logo's and headers. SVG loads very fast!)