One of the obvious issues with social networking software is the lack of connection among different services. I have a Facebook account, a MySpace account, and even more contacts in LinkedIn. I have some flickr images, some YouTube videos, then there are those bookmarks or blogrolls I might want to share. Not to mention all the blogs where I contribute or websites I manage.
Until there is a way to connect all of this social data, at least there are some services designed for creating a single profile with pointers to your various social presences. I have started looking at these and just signed up for ProfileFly yesterday. I haven't added very many links yet, but there are a number of options. Check it out--it's an interesting idea.