I was missing Dropbox on Pandora too. My workaround is clunky but working for me:
* install Pandebian
* install Grsync in Pandebian from it's repo
* install davfs2 in Pandebian from it's repo
* make an account at box.com
* follow this
guide on mounting box.com as webdav
Then everytime you want to sync do this:
* start Pandebian
* start Pandebian share (to share one of your SD cards with Pandebian - actually you might have to do this already when setting up the box mounting, I'm not sure now)
* mount your box from Pandebian's terminal (follow the guide above)
* start and setup Grsync in Pandebian (mounted box as a remote dir, your local dir as target dir; read the info at exclamation mark icon next to Source and destination field in Grsync)
You might get some errors during the sync but for me there was never a real problem with files that were synced.
I'm auto-syncing box.net with one of my Dropbox folders locally on windows desktop PC via normal local folder sync app. Clunky but woking
Nonetheless, I'd like to see some Pandora native folder (semi)auto-sync solution too. There is nice python based
Dropbox client for N900 which might be an option if somebody with python skills would look at it.