Andrei Zmievski [1] pointed me to the mod_auth_sqlite [2] by Ikebe Tomohiro [3], an Apache 1.3.x module that allows authentication from the information stored in an SQLite database. You might also like to have a look at mod_auth_mysql for either Apache2 [4].
[1] http://www.gravitonic.com
[2] http://freshmeat.net/projects/mod_auth_sqlite/
[3] http://shebang.jp/mt/
[4] http://sourceforge.net/projects/modauthmysql/
