Visit Facebook, Myspace, Friendster - and one other social networking site of your choosing. Compare your impressions of these sites. Note that you probably should register and log in to get the complete picture.
Facebook - Facebook is a social networking site that is constantly changing. I don't log in that often so buttons always get rearranged and I can't figure out where they are. Not sure why they insist on changing it though. Originally it was a fairly good social networking site where only college students could join since you needed a college email to join. But now that they opened it up to everyone else, there is an increasing amount of fake profiles which was a big problem in myspace. Overall facebook is a great site that allows you to keep in touch with virtually anyone and everyone. You can easily share pictures, videos, and links. Although some of the newer features seem unnecessary. You can comment on someone's wallpost. Why not just post on the wall instead? I guess this allows for more detailed conversations that are visible in a convenient location.
Myspace - Myspace is one of the earlier social networking sites that existed before Facebook. It has many features that exist in Facebook, but the main two differences that I have found is the ability to upload music on Myspace and the rampant amount of fake profiles that just send you messages attempting to lure you onto their adult websites. Myspace also lets you make changes to your page which gives it greater customization, but that tends to be used poorly by people who plaster their pages with images that end up making the page unreadable. Myspace for the most part has lots its edge on social networking to Facebook.
Friendster - Friendster is an interesting social networking site since most of its users are located in Asia. It is the icon of social Networking there. Unfortunately that happens to be its main standing point. For the most part its quite similar to Facebook. Which may be a good or bad thing. If they expand globally they might become a major competitor to Myspace and Facebook.
BrightFuse - This is a new professional networking site created by Careerbuilder.com. At first glance this website looks quite similar to LinkedIn. Upon closer inspection I noticed it has more social networking features similar to Facebook. It has a "Working on section" which is similar to a status update on facebook/twitter but has a more professional association. Brightfuse also has a built in blog feature. It was created recently and is probably relying on the fact that they already have a large userbase from Careerbuilder which they can easily transfer over. It's careerbuilder usebase and its extra social networking features may help brightfuse stand out compared to the already successful LinkedIn.
P.S. I didn't realize this post was supposed come before Social Networking. =P.