Use CPPSERV instead
mod_plsql is fine idea, and will work for simple applications, but for anything even mildly complex, one needs real application server. My personal recommendation is CPPSERV: it is an application server that provides very Java Servlet-like API to C++ programmers, and also contains CSP (C++ Server Pages) parser.
An open, cross-platform journaling program.
A scientific plotting package.