For bulk loads into Oracle (I understand thatís the db that you use) nothing beats SQL*Loader. Itís quite flexible: various load formats, selective loading, multi-table loading etc. etc. The configuration can be a bit tricky but normally thatís where the DBA comes in :-) There are also many third-party (loading) tools which offer additional features. I was addicted to Toad making the life of the Oracle developer a lot easier!
I have tried doing bulk loads into Oracle with lots of simultaneous connections and it worked very much against me. Especially when you use connection pooling (Oracle 9i + WebSphere 5).