Here's a place to put your W.I.Ps ( work in progress) for a good old crit like drawover/paintover.. Try to take each others varying styles into consideration when you take a red marker to it, i.e. no plainly redrawing images in your own style lol.
How it works:
If someone posts a "WIP" you can repost it with a paint over or drawover to give a different perceptive on their work. Or you can simply crit their work on their post. Simple really.