[dmb]

Python: - the first time I concisely solved a seemingly complex problem with a few list comprehensions and a well thought out structure of maps and lists

C: - Using an include file as a simple database and redefining a macro to form a primitive code generator (first saw this in a CPU simulator)

Haskell: - SPJ's books on implementing functional languages -- the simple beginning pieces seemed to generate more Aha moments (pretty printing and parsing)

While none of these are specific to the given language, they represent points-of-no-return for a change in the way I think about solving (or even representing) problems.