There is a commercial utility call Database Unloading by Data Extraction, DUDE. It is able to extract data with database down or without any mean of recovery. Certainly for DBA, we used it when database is seriously corrupted, and cannot bring up. Then we use it to extract the data from each dbf files.
As of 30-Oct-2008, the version is DUDE version 2.6.6, or called as jDUL 2.6.6 for the Java version.
The output can be Oracle dump file, or flat file to be used by SQL*Loader
Unluckily, it does not support index organized table (IOT) and ASM file system
Demo version is able to extract for 10 rows, while cheap 7 day license can be purchased for disaster recovery purpose