I've been able to play with a Lisp again using Rich Hickey's DotLisp as an immediate mode interface into Microsoft's .NET Framework.
I have never used Lisp on a Unix system.
Make your own opinion of me from my newsgroup posts: Search Google.
Some important Lisp links that should be mentioned somewhere:
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John McCarthy's Home Page -- The inventor of Lisp and futurist.
Specific Lisp papers on that site: