Unsupervised learning in neural network

Neural networks are often used for feature extraction and dimensionality reduction. Google autoencoders and RBMs. One of the original papers is this one.

For clustering, I guess you would be looking at SOMs and Neural Gas. These are big in the neural network community but I have the feeling they are a bit frowned upon in the machine learning community.

My bet would rather be to extract features or learn a metric using an autoencoder (my current favourit is this) and then use k-means.