I am suprised this has not been posted yet!
A region-free firmware for the Pioneer DVR-106/A06 is now available on Pioneer Region-free DVD Firmware Page.
Haven't tried it yet since I am in the middle of a large backup. I will try it in a few days since I can't afford the drive to be down right now!
The readme file is as follows:
Drive: Pioneer DVR-106/DVR-A06 (Dual format DVD+/- Burner)
Firmware Rev.: v1.07
Patch: RPC-1 (Region Free) + 2xDVD-R + 12xRip (pressed DVDs)
Date: 2003.09.22 - 23:03 GMT
Release Notes: This is the release version of the 2x4all DVD-R including the anti 2x Rip Speed limitation patch. The 2xDVD-R patch DOES NOT alter the write strategy for Pioneer 2x authorized media, or any media that is burnt at 1x or 4x PROPER BURN OF 2X NON AUTHORIZED MEDIA IS NOT GUARANTEED!
Flashing Instructions: Make sure you don't have Intel Application Accelerator installed. Then run UPGRADE.BAT. You shouldn't have to downgrade if you flash from Windows
Useful Links: http://forum.rpc1.org/ (See: DVD-R/RAM/+RW)
Thanks to: Flash, nicw, Gradius, zaitec2, Vlad & Igor...