mod_pointer is an Apache module for making domain redirects easy. The configuration part of the mappings are handled in either a MySQL or Postgresql database, or in a NDBM or SDBM db file, which makes it it easy to build a web-based interface for letting users change it on their own.
rpaf changes the remote address of the client on incoming proxy requests. It is used in backend servers that needs to know the IP of the client, and works in conjunction with mod_proxy_add_forward (which sets the X-Forwarded-For header). When an X-Host header exists rpaf will take the hostname found here, put it into Apache, and update the virtualhost settings so that you can serve virtualhosts on the backend. It includes modules for both Apache 1.3 and 2.0.
The SQL Schema Repository is a collection of SQL schemas that saves the trouble of creating common parts of your SQL scripts everytime you start a new project. It contains schemas for a Country DB and the American States. All the schemas are available for both MySQL, Postgresql, and Oracle.