The ZODB (Zope's object database, which can be downloaded and installed separately from Zope) and Durus (part of the Quixote family, I believe) are both high quality persistent Python object stores that are used heavily for web sites.
I've never used the ZODB outside of Zope, and haven't used Durus yet. But there may be some examples written up about how to use them with mod_python. You *might* even be served by the built-in 'shelve' module. http://docs.python.org/lib/module-shelve.html -- http://mail.python.org/mailman/listinfo/python-list
