If you store your config in a RDBMS, how do you want to get the configuration info for the DBI connection? I stick to human-readability, myself. I've used the basic INI-style stuff, and abused Data::Dumper once before, but my favorite is YAML. I can often make a human-readable config file, that is parsed into the exact data structures I want to work with.

Update: Also, if you're using a DB for key-value pairs, a table with tons of fields is horrible to edit. Use a two-field table, and make a class that uses AUTOLOAD to grab individual keys. If nothing else, you will strike fear in the hearts of your co-workers!