Central password storage tool that multiple users can access with privilege levels
Solution 1:
I would strongly recommend looking into Secret Server. It has the features your looking for plus logging and isn't very expensive. If you prefer open source and free check out Webkeepass. We started using Webkeepass but switched to Secret Server as it's much more user friendly.
Solution 2:
We are trialling LastPass Enterprise. I figure the easier it is for users to use the less likely they are to end up writing down passwords or copying them into their clipboards etc. It is certainly not the cheapest alternative and does involve relying on and sharing with a third party.
Still just in the trialling stage and still on the look out for an option with a better user interface and individual password expiry. Its integration into the browser is pretty killer though.