Of course I have to rate this site as #1 ... I'm addicted!! (dear family knows this!) 
I thought I would share 2 others that I enjoy also...
www.toyvoyagers.com
This site is a great hobby site. I have been pretty active on it for a year now. I'm taking a hiatus from it since I have been flaring up a lot lately and need to focus on real life issues. I have also seen it as a learning place also. Homeschool students (younger) could send their toy and learn about the country's culture and maybe what they do for school there. Hosts are available from all over the world. What you do is pick a toy from your collection (to be frugal), register it (free up to the first 5 voyagers), set missions for it to complete and start looking for hosts. You can choose to host or not. If you do, the only thing that you are out is postage. (And gas money if you go extra places to show things off... which you can see examples of on the site). If anyone remembers Jayme that lives in Japan (she hasn't been active for awhile) got me addicted to this site and it is very interesting! I have 2 animals traveling... one is on a "German trail" and then will move to the "European trail" then to Moscow!... the other is on his way from Germany to Thailand then will go to Canada, then the Czech Republic! (I did have another but it got stuck in Finland for awhile and he's now sitting by my bed until I feel like letting him travel again).
www.chronicbabe.com
My friend that I went camping with told me about this site. Pointed more towards women, there are men on there, it's a social networking site for those who have chronic medical conditions. I am still new to the site but it's very friendly. It's not a site for complaining but for bouncing ideas off and sharing with others who have chronic illnesses. I would rate the site as very G/PG. I'm still feeling my way around it. The one thing I am not too happy with, and I think it can be changed if needbe, is that my real name appears on every post. It's got a facebook-type setting and there is also a chat room.
oh, and cannot forget the site I check every time I'm online for a smile...
www.glasbergen.com
I'm not confused. I'm just well mixed. ~Robert Frost
Laziness may appear attractive, but work gives satisfaction. - Anne Frank
I can do all things through Christ who strengthens me. Philippians 4:13
Married my Blessing 10-16-10 :)
Became an Auntie 12-10-10 :)