how do you keep track of tacit knowledge and collaborative stuff?

I’m part of a two-librarian team tasked with research solutions for what we’re calling a knowledge bank or internal repository.

What kind of solutions do you implement at your library for this? We’re currently using a shared network drive but it has many problems and doesn’t meet our needs. Shared files are constantly deleted or misplaced (inadvertently) by users. The network isn’t accessible from off-campus. People can’t really share narrative, short of creating a word document and putting some thoughts in it and hoping people intuit from the file name why it might be useful.

Tools already under consideration (or nixed from our list): Drupal, WordPress, various wiki products, NING, CONTENTdm. What am I missing?

Full disclosure: I just want it to be Drupal, but due diligence means I gotta consider some alternatives. (: