Lambda the Ultimate

Programming Languages and Lambda Calculi looks like a comprehensive treatement of the semantics of typed and untyped call-by-value programming languages. I imagine if one had a basic undergraduate education in programming language theory and wanted to get up to speeed in a hurry this would be a great resource.

CLPython is an implementation of the Python programming language in Common Lisp. It is developed by Willem Broekema with support from Franz Inc. CLPython is released under the LLGPL.

You might enjoy browsing the source code.