Dopeness. SUMO Paint is a free image editing software that gives you the opportunity to create, edit and comment images online with powerful tools and layer support. I tried it for a quick bit, and I barely noticed any lag using it; then again, I didn’t have so much layers yet.
Being that its a Flash-based application/tool, that’s a whole lot of user-support and market share. That’s remarkable as Designers and non-Designers a like can use it whether they’re away from their workstations or just don’t have Photoshop or applications like it at their disposal. Some of the featured I’m digging are: Shape Trails, Symmetry Tool, and it’s support for Cooliris’ 3D Gallery (formerly PixelLens).
Anyways, go check it out and let your mind free. You may access the application directly via sumopaint.com/app/