Definition: An ETL process data to load into the database from a flat file
A. Extract
B. Transform
C. Load
Not exactly an ETL tool, but I've recently felt a sense of liberation since switching to make/python/psql/wget... for my ETL needs. Make is probably the cornerstone as it handles dependencies (think foreign key ordering with schema introspection) and parallel loading in a very intuitive way.
Forgot to mention that I do something more like ELT. Postgres itself is the best Transform tool.
