A trivial RBM in python (praise numpy)
It uses simple 1-step Contrastive Divergence (CD-1) as described in the wikipedia write-up on RBMS.
It does nothing else clever at the moment, although f.ex. momentum would be easy to implement except supporting momentum.
badtest.py demonstrates a fairly simple useage scenario.
Oh, you'll need numpy and scipy installed, but it has no other particular dependancies.