Putting my money where my mouth is

As part of my job, I've been asked to think about the design of our website (which does not exist yet) and consider how more interactive possibilities might be incorporated. A link to my collections management blog, obviously, or if we could get it in the frames without leaving the main site would be better.

But what else? Podcasts are out (don't have the time, the tech, or the passion). Something where people can talk back, but not just a link to an email address. Full out forums are too big and too... well... dated (not that they don't work, but those are really designed for super committed special interest groups). Starting a Flickr account would be awesomely cool - and flickr has some widgets that look great on blogs and which could be interesting on a museum website. Twitter? Twitter seems cool and hip and all that, but is the user base really large enough that people would understand it and buy into it?

I think what I want is like "Guestbook 2.0" or a mini forum board. Where people can leave feedback and it shows up on the site immediately and can be responded to by museum personnel (ie, me), but requires little to no tech savvy from the end user, but doesn't look, er, lame. A guestbook with comment threading? Does such a thing exist?

And what else? Easy to use, easy to understand, and minimal work investment on our end. I know you're creative people reading this feed; let me pick your brains.

Edit: Gadunk! A Facebook group/profile! This IS a college campus after all. That whole guestbook 2.0? I want something like The Wall from Facebook to be on the site (except comment threading instead of wall-to-walls). Now where does one get such a thing....