TextDB: If you don't have access to a database but you do have access to PHP, and you want your web data stored in a database, then this is what you're looking for! Full sql compatibility is planned as well as a perl port.
This is OS-independent and is licensed under GNU GPL, has a web-based interface and is developed using PHP. (check out: http://sourceforge.net/projects/textdb
Berkeley DB (BDB): This is a computer software library that provides a high-performance embedded database, with bindings in C, C++, Java, Perl, Python, Ruby, Tcl, Smalltalk, and many other programming languages. Berkeley DB is redistributed under the Sleepycat Public License, an OSI and FSF approved license and runs on a variety of operating systems including most Unix-like and Windows systems, and real-time operating systems. It comes in three different editions: Berkeley DB(originally written in C), Berkeley DB Java Edition, Berkeley XML DB (check out: http://en.wikipedia.org/wiki/Berkeley_DB