I posted this a few months ago, but wanted to share it again since it's been a while. I collected some grammar charts in a google doc, and some very helpful people from the Duolingo community contributed - I hope it's useful to some of you!
GOLD, thank you ! You should add http://www.lsa.umich.edu/german/hmr/Grammatik/Gender/Gender.html its really useful :) and http://i.imgur.com/tVzEY7k.jpg, everything should be combined
Thank you very much!
I'm no way near ready for this but I imagine it's going to be a great gift when I am.