Thanks to Gerry Mckiernan for pointing this out, in a post to Dig_Ref:

Top Ten Facebook Apps for Librarians (in 3 parts) from Ellyssa Kroski’s iLibrarian blog

Apparently, UIUC is the only library that currently has an app for its OPAC, but they’ve posted the code, so others could follow. Also there’s a search app for JSTOR. May I suggest other search apps for other online databases? Perhaps by vendor?