Eathena-test-server is a project mainly written in C and PERL, it's free.
eathena test server
This is just our eAthena version. We store our scripts, items and monster databases, etc. in a separate git repository called tmw-ufb, available at:
http://gitorious.org/tmw-ufb
Note that this repository contains more than just the contents of this data directory. Either set up symbolic links or just copy the server executables into it.