This article from Fumsi about the use of social media at the Orkney Library and Archive is a really great example of this kind of outreach. I hate the word “outreach” but haven’t found a good alternative at the moment… Orkney’s activity does look like outreach in terms of pushing out a message more than interaction/having a conversation though.
The Archive blog (updated daily) is at http://orkneyarchive.blogspot.com/.
I visited the Library & Archive last summer when in Orkney for St Magnus Festival with Choral and was really impressed – a welcoming building, with a real buzz about the place. Didn’t see any of the food which is a regular feature of the blog though… (but can highly recommend Orkney Ice Cream in original flavour…)