Have you considered using Amazon SimpleDB? Its a very simple and fast way to persist data. Avoids the scaling and implementation headaches associated with a typical database.
Huh?
Sorry, that really wasn't meant as a criticism of LISP.
Common Lisp certainly does have good database support: CLSQL probably supports whatever combination of OS, Lisp implementation, and RDBMS you need.
ORM tools and other object persistence solutions are there too. http://common-lisp.net/ is a good source.