To get an idea of what Elgg is, and how it can be useful to you, there are a few links below:
This is a podcast interview with the two founders of Elgg. It is a little date, and has an educational focus, but it is still a useful intro, and if you use a little imagination, you can see how their examples could be applied here. http://www.edtechtalk.com/EdTechTalk8
Related to the previous link, there is a screen capture of someone going through Elgg and actually using it. It is a 70mb WMV video http://edtechtalk.com/video/elggtour.wmv
The Elgg site itself has a good list of features which were the basis of the previous post http://elgg.org/features.php
