Over the past few years, I have been dabbling with different ways of offering various web services to help my family share content and stay in touch. I originally started with a so-so wiki that didn't work that well (mostly my fault). I then moved to Drupal where I intended to have a story and biography area, photo gallery, and discussion forum. The stories area did okay, but none of the other parts of the site caught on. That was probably good in the long run since I have had a love-hate relationship with Drupal in the past and wasn't up to spending tons of time to massage the interface.
Now, I have decided to install various open source web apps that have a focused goal and perform their narrow function well. Currently this includes Gallery v3 for sharing photos and videos, webtrees for compiling/sharing our family's geneology, and a MediaWiki install for various documentation, news, and stories/bios.
The biggest hurdle with implementing several sites is supporting some form of central login. It is hard enough to show family members how to use some of these sites, and would be hopeless if they had to manage different logins for each. I am currently using LDAP as the central authentication backend. This works okay with a Gallery plugin, but I'm having to work a bit to get LDAP working with MediaWiki. Webtrees doesn't have LDAP support currently, but it has been discussed as a desired feature.