Oracle external tables [orafaq.com]
Oracle has a built-in facility for accessing text files as if they were tables in the database.
This is a screaming fast way of loading data into a table, and it is easier than SQLLDR, plus you can keep your foreign key constraints etc..
I used this at United eWay to replace some pages that were taking several hours to load data from a CSV file. The new script took a second or two instead of more than 18+ hours to run (and it actually never completed).
Combined with the MERGE SQL command, this is pretty powerful stuff.