What do I learn next?

[theSage]

I know Python and C. What do I learn next?

--edit--

I have not had formal training in programming so I am looking for languages which show me new things.

[tjr]

Lisp. Specifically, try Scheme. More specifically, try working through The Little Scheme and Essentials of Programming Languages, both from MIT Press.

[theSage → tjr]

I had been hunting around for Lisp tutorials and literature. I stumbled upon writing a lisp interpreter in python called Lis.py

All this while I had been thinking Lisp is something novel and only for kicks. Thank you for letting me know about Scheme.

[tjr → theSage]

There are other good Lisp dialects too, of course, but Scheme tends to be especially well-suited for learning the concepts of Lisp (or of computer science more generally), and has numerous good books towards that end.

Also, oops on a typo that I can't fix in my previous post now: The Little Schemer.

[kristianp]

SQL and database normalisation. Then datawarehousing things like star schema.