I am unsure on what's the best way to add a new RDF writer to Jena and/or RIOT.
Is there any documentation about this?
Documenting how developers can add new readers/writers to Jena could be quite interesting and useful.
Using RDF as gateway between different formats|data models is quite an interesting and useful thing to do (and it's a way to tackle the N2 problem when you need to translate N formats from one to each others).
A good and inspiring example of this is: http://simile.mit.edu/babel/
Documenting, or making it easy and obvious, how to add new readers/writers to Jena would enable others to do something similar to Simile's Babel (and they might contribute back readers/writers to Jena).