Advanced export option: Script
This isn't completely worked out in my mind but it's based on the flexibility we have in TextMate for adding bundles. You can use any script and have a few environment variables at your disposal and you can do pretty much whatever you want. But these scripts and settings can be packaged up and installed.
For OTJ, that could mean something like
Export >
CSV XML Text Advanced
Advanced >
my cool pdf generator
#!/usr/bin/python
from amara import bindery
doc = bindery.parse(OTJ_EXPORT_XML) #could be OTJ_EXPORT_CSV or OTJ_EXPORT_TEXT
#do stuff and output stuff
something along those lines. I can do this manually now of course but that means a copy paste into TextMate, etc.
Otherwise perhaps just add a Script option with a scripts folder for OTJ where we can store and run scripts in this way.