I personally believe that the best way to introduce someone to blogging is to point them to blogger.com. Nothing out there tops their very welcoming 3-step approach to setting-up a blog. It is the first blog system I signed-up with and the one I continue to find the most appealing.
Derek has a very-nice breakdown of the various blogging systems out there.
Beyond blogging, there's also Social Networking. A few sites such as Friendster and Orkut have entered this field a couple of years ago. LiveJournal, primarily a blog system, also has a notion of "friends" and social networking which blogger.com lacks. Now Yahoo and MSN are looking to blend these concepts and more with burgeoning all-inclusive content sharing portals: Yahoo 360 and MSN Spaces. Those systems make it easier to establish connections around common interests and develop new interests around social connections. For technical and security reasons, those social networks will never allow you to customize look, feel, functionality of your online journal content, to the extent that pure blogging systems do. Which is partly why I still favor blogger.com over most alternatives out there.
The king of Picture Sharing remains Flickr.com, which integrates very nicely with many of the blog systems out there.