I had a cool idea this morning for a new game kind'a thing we could do... Its probably the best way to improve, my suggestion is "Replica the Design". Demonstrating an existing signature, participants will be given a stock and they have to recreate the sig as best they can. Certainly could be a challenge
I got Adobe Photoshop on my iPod! Link
I got it a few months ago but just remembered it. Obviously it doesn't include all the features of PS. Still cool for on-the-go editing though.
Also, I think we should maybe have more people posting stock/render etc. packs in one place for people to use either they could make them or they could have found a really good stock pack to share.
I have just joined this gfx site, and it is full of everything that you could need. The only downside is that there isn't much/anything about GIMP, but at least nearly all of the resources can be used in GIMP (illustrator stuff can't work in gimp, but there aren't many of them any way).