It seems social networking sites are growing up. Initially thought to be just for teenagers, sites like facebook, twitter, linked in and friendfind are quickly growing in popularity for 30 somethings all the way up to seniors.
Facebook is likely the most popular social networking site. Facebook allows users to connect with friends, collegues and family. One benefit of Facebook is it promotes what I like to call "microconversations" through the newsfeed, which keeps you abreast of all your friends activities. With facebook, you can quickly and easily update friends on your activities, comment on photos and message friends and family. Personally, I am much better at keeping in touch with friends and family members who are on Facebook than those who are not. If you are concerned about safety you have good reason. Although Facebook is great, there are risks involved so it must be used with caution. Ultimately you have the power to decide who has access to your information and photos. Don't accept every friend request that comes your way for fear of offending. If you have no idea who someone is, simply ignore the request. On the flip side, if you send a friend request to a long lost friend take the time to include a personal message to remind them how you know them. For personal use I recommend setting everything to be viewable only by friends, not friends of friends. Doing this allows you ultimate control as you alone control who is in your friends list. It is a good idea to occasionally go through your friends list and asses why someone is on your list. A good rule of thumb is if you haven't had any contact (on facebook) with a friend in 6 months, delete them from your friend list.
There are also many third party add-ons and applications for facebook. I recommend using caution when using these applications as you are allowing them access to your information and in some cases your friends information. I personally do not use any of the games or add on apps for facebook due to a bad experience with funwall. I would up having to format my hard drive after it was infected with a virus, likely from a link I clicked on my funwall.
I personally use linkedin, facebook, and twitter, although for different purposes. Facebook is purely social. Social media is useful for people of all ages, as long as it is used with caution.
Update On Dec 07, 2010: It is important to pay close attention to your sharing settings on Facebook. Unless you want anyone with an internet connection to be able view your photos, make sure you have them visible to friends only (every album!). Otherwise you can't be certain who is "creeping" your photos.