Low level
Stanford UFLDL tutorial
Geoff Hinton's Coursera class
More tutorials
Mid level
Good reading lists
[a]
[b]
High level
Recent, impactful papers:
[a]
[b]
Technical tools
Caffe
Paper on caffe
Cuda-Convnet (Alex Krizhevsky's original imagenet code)
OverFeat (Yann LeCun's group) and Torch
Theano by Yoshua Bengio's group