Heh, when I saw the thread title, I immediately thought of Frank Zappa and Wesley Willis.
I don’t know much about Willie Nelson, but I think he released a whole lot of albums.
Ravi Shankar.
I see they are looking for donations of any of his original works on 78’s. That alone is impressive.
I’ll stack this list of credentials up against anyone, anytime, anywhere:
http://www.ravishankar.org/bio.html
This man is a deity.
Check out his daughter’s site too, she’s both exceptionally beautiful and exceptionally talented.
And Norah Jones isn’t bad looking either (she’s another of Ravi Shankar’s daughters.)
Johnny Cash may have recorded over 1500 songs, but he didn’t write anything near that many.
My orchestra teacher in 9th grade said Telemann was the most prolific composer ever, I don’t know if thats true though. He said Mozart was the 2nd. Bach I would have thought beat them both but I don’t really know. Those 3 sound like good candidates, especially Mozart since he composed starting at a very young age.
In terms of sheer number of compositions, Mozart’s catalog is in the 500s, while Bach wrote over 1,000 works. Of course Bach lived much longer than Mozart, but I think even in terms of annual output he has the edge. OTOH, Mozart wrote more large-scale works, operas in particular.