in reply to DBI vs MLDBM/GDBM_File, etc.
Going with a full on RDBMS will probably be overkill. Going with a quick and dirty db like MySQL or MS access is fine, but you'll have to pick up some SQL (not hard).
Going with DBM is fine for simple data.
If you've got a very large data set you'll want a full RDBMS for the data caching and rich indexing options.
my advice is do what will get the job done now, then pick an RDBMS and learn it once you can afford to spend some time clambering up the learning curve.
I use Win32::OLE (ADO) and MS SQL at work. At home, I try not to have data that won't fit in main memory.
I'm not wearing any pants