METAKIT is a curious mix of flatfile, relational and OODBMS features with a
small footprint, and a big following.  For those who don't need a heavy-duty
SQL solution, it is tight and fast for <100,000 items, with a snazzy ability
to dynamically change data structures on the fly.  Interfaces are available
for Tcl and Python, with Perl support promised soon.

WWW: http://www.equi4.com/metakit/