Plurk

I must say i'm very impressed with Plurk, my favourite social-networking site. The concept is very simple: describing our daily actions based on actual timeline. There are two advantages that Plurk has compared to Twitter:

1. Emoticons. Twitter doesn't support native emoticons, unless your Twitter application adds it. In Plurk, you gained emoticons through Karma which should grow if you plurk regularly (it can drop too if you post too much or if you leave your Plurk account more than one day).
2. Real time updates and timeline-based. Plurk has integrated real time updates by using Comet infrastructure and you will other's comment on your account popping up as soon as they press enter on their screen.

Of course, there are some disadvantages of Plurk also, for example the Karma concept. In order to maintain or to gain your Karma, you must update your Plurk regularly. For some people, this would be daunting task, but for those who enjoyed Plurk, it will not be a problem. The other problem is to find your friends at the beginning. It doesn't have any friend-suggestion feature like Facebook or Twitter. For some people, it's normal to find it hard to find their friends at the initial.

Plurk may not be as popular as in Twitter, but for me, i think it's still the best social site.