The first book I clicked on is not free.
http://hackershelf.com/book/129/97-things-every-programmer-s...
http://hackershelf.com/book/129/97-things-every-programmer-s...
If it isn't, all you need to do is flag it.
http://programmer.97things.oreilly.com/wiki/index.php/Contri...
The site appears to use a loose definition of free.