Vendor Free

Wikis

Mediawiki (http://www.mediawiki.org) is probably the premier wiki engine available. It is the backbone behind Wikipedia and thus has been proven to be able to handle any project from small to large. The complaints I get about media wiki are that it isn't as user friendly as it could be and that the wiki markup (the way you format the content) is a little confusing and the learning curve is higher than I could be.

TWiki (http://twiki.org/) claims to be the Open Source Wiki for the Enterprise. I have heard a lot of good things about TWiki including that it has an improved user interface. I haven't had an opportunity to install it because it runs on perl. The only downfall of Twiki, that i've heard of, is that it is slow when trying to handle a massive wiki project, but for users of just a handful of users like a university committee it might be the balance between functionality and usability.

Blogs

Wordpress (http://wordpress.org) is with out a doubt the powerhouse in open source blogging. you can sign up for a free blog and try out the interface, which, seem to be pretty easy for people to use. My experience is that with most of these products the administrator creates a blog, creates some users and the users go to town. Wordpress seems to be one of the products I get the fewest questions about.