Hi Massimo,
this idea is making me shiver a little bit, I hope for the wrong reasons.
First of all, who would be able to commit to these libraries ? Would a library's author be the one to accept patches ?
This github repository would have different permissions for each subproject ? (so that only the library author and whoever he choses would be able to update it ?)
Existing repositories with working libraries wouldn't be penalized unless they move to this repository because they would be less "official" than the others ?
Would there be requirements to fulfill to have your library be part of this repository ?
What about licenses and copyright ? The projects out there are heterogeneous in this aspect.
Isn't the database you are working on enough ?
Thanks for reading,
Riccardo Galli