[open-bibliography] comprehensive bibliographic database of "open" resources?

[John Wilkin]

All,
Of course I can think of a bucket-load of reasons why this would be impossibly hard to assemble and maintain, but I'm still curious:  has any organization tried to create a database of essentially "open" bibliographic resources?  In this case, I'm interested in something broad enough to include CC, PD, etc.--i.e., resources that can be used (at least in scholarship and teaching) without fees paid to the maintainer of the resource?