Neopets- Good for all ages, fun site with virtual pets, games, and more... ((look me up, I'm lupe_lover25))
The Cloaked Territories- Best for people who like to role-play (("rp")). I go by Areaen and am the moderator/creator of this site. **Recommended for ages 12 and up...
Lord of the Rings.net- Great for all ages of Lord of the Rings fans. :D **Some scary images for small children.
**Please note that I cannot say that all links from sites linked here will be appropriate. These websites are, however, insured unless otherwise stated.