Create an error routine to execute when something goes wrong, present a happy screen to the users letting them know that some sort of non problematic (don't panic!) problem has occured and to contact X if they desire.

then internally, log what really happened (the web logs might suffice instead), or perhaps shoot an email to yourself with the real error so you can dig in and fix it.

for instance, if we can't connect to the database, rather than present the ORA error messages, we just post a "system down" message that assures the users that it's temporary, and provides information for them to contact support.

good luck!