For self-education, I have used a wide variety of languages, including BASIC, APL, Pascal, python, and bash. For computer search and verification, I have used bc and awk: bc primarily for "small" bignum computations and awk for its nice handling of defaults and recasting between string and integer types. Awk is also similar to python in that a user can rapidly prototype with it.
Gerhard "Ask Me About System Design" Paseman, 2010.02.22
