If you're interested in compiling a physics text from raw materials with your bare hands: come to the Boundless offices in Boston this weekend for a booksprint.
http://textbookhackathon.eventbrite.com/
There's an intro session Friday from 6-10pm, and people will be working on the book Sat 9-9 and Sun 9-6.
I will be there with my best doppler effect outfit.
Cheers, SJ
PS - I don't know anyone at Boundless, so this is also a good chance to meet them and see what they're up to in person. Right now the Saylor Foundation is still my favorite org tackling the open 'writing textbooks' problem.