Hello galaxywatcher,
I have read your proposal and I know I can get this done quickly and professionally for you. Just to double check, you're looking for a script that will test default ports, both UDP and TCP, for various database systems to see if they are running. I would tackle this project by writing a Perl script that would read from a text file containing a list of known database systems and the default ports that they run on. Once I determined that a port was active and listening, I will then make an attempt to connect to that server (obviously without valid credentials) and if I can connect then I will report what software it is.