Ok, today I'll plug the blogging app that I'm using here, MovableType.
One of our radiologists asked about possibilities for setting up some kind of online logbook that residents could use to log the procedures they perform. My first thought was that it sounded like something a blogging app could do. I searched the web looking at different blogging apps that met 2 criteria: source code available, and low cost (preferably free). This one had the most features for the best price that I could find. Installed it, got it running, played with it a little bit, then they decided to go with some other software.
So MovableType sat around on my system unused for a few months, until I decided to try out the blogging world. Cranked it back up and here we are now.
Turns out that MovableType (MT) is a pretty flexible app. It's written in Perl, easy to install, and is extremely configurable through the use of plugins, templates and style sheets. One of the plugins lets me put the latest weather for just about any location I can find. Very slick. There's quite the list of plugins available that do many different things. Plugins are also written in Perl, so should be pretty easy to write, if you know Perl (which I don't).
If you're searching for blogging software for your site, I'd check this one out.