I know if you have the MVH-P8200 (without the BT on the end) you can get a CD-BTB200 attachment via the "IP-Bus" link on the back. It has A2DP/AVRCP bluetooth audio streaming but it costs $140, and I have no idea if it will work with the MVH-P8200BT since it already has bluetooth.
Also for $36 you can get a CD-UB100 that will give you a rear USB port via the "IP-Bus" link as well. It has a few flaws but it's better than nothing...
There is a guy who has a good blog about it the IP-Bus accessories here:
http://blog.komeil.com/2010/03/pioneer-mvh-p8200bt-review-mech-free.html .
I'm debating between the MVH-P8200 with a few IP-Bus accessories and a Sony DSX-S300BTX.
Pioneer MVH-P8200 + ICD-BTB200 + CD-UB100:
(+) Kick *** color display + video
(+) Pioneer's good reputation
(+) SD card reader
(-) No slide-out mp3 player tray
(-) Lots of cables and audio quality loss via analog conversion
(-) Clunky interface - hard to navigate menus
Sony DSX-S300BTX:
(+) Cool slide-out mp3 tray
(+) Supports mp3 disks/players in MSC and MTP modes
(+) Bluetooth is built in - no extra cables
(-) no LCD display, might washout in bright sunlight, no video
(-) Sony doesn't have the best reputation for car receivers
I've heard that when using lots of mp3s, both units are slow at loading and refreshing and require a FAT32 file system. They say browsing by folder is slow and they have to recreate the database whenever you switch inputs which can take several minutes. People have been getting around the issue by using 5000 or less mp3s even though they have 64gb thumb drives for $80. If the rumor is true, then that sux! Does anyone have any first hand experience with either of these units to verify this? Perhaps if the files are arranged in a certain folder configuration then these issues could be avoided?
lol! - I just realized that the link I posted to komeil's blog was the same as the link in the post above mine - except it was posted by komeil himself...