I've squandered some serious time there playing "photoshop battles"
It really honed my photoshop skills to the point where I can blow most of the 13 year old kids I am competing against out of the water with cheesy 10 minute renderings of kianu reeves and whatnot. I usually don't win, and that's because I the angles I take are played from an age group that isn't wasting much time on photoshop battles
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It was hard to get a feel for the layout, because it is soooo basic and cheap- but it works, AND it let me hone my chops on quick turnaround times for photoshop entries, however, there seems to be an endless base for discussion groups, but the limited comments I've seen that have spilled into the photoshop section seem to be in line with "yahoo" user comments, so who knows....
I'm sure you can find some quality discussion there, and I'm sure it's there, but I haven't really i found it yet.
Good luck.