Serialization + persistance : in a few lines of code, compress and annotate Python objects into SQLite; then later retrieve them chronologically by keywords without any SQL. Most useful "standard" module for a database to store schema-less data.
ShelveDB is a pure python SQL-like database engine, where queries are preformed in analogous python syntax. It uses only built-in modules and shelve as the data structure. It has regularexpression searching, plus native python typing and type checking.