I constantly ask myself if I really need such a site. And the answer is "Yes!" Why do I need it? Of course not to boast about myself and my work.
I live in the Far North of Russia and the weather doesn't often allow the pupils come to school. They have to stay at home. And we lose the precious time of the lessons. Some pupils are very interested in studying English. So my site can help them to work and do some exercises to improve their level of knowledge. It's the first advantage.
I have been working as a teacher for a long time and have many useful materials which can be helpful for my younger colleagues. So I can download them onto my site instead of having them on my computer. It's the second advantage.
There are many different olympiads and contests which are held in distant way. I would like my students to know about them. So I can give this information on site. This is the third advantage.
There are some points against having a personal site. And the most important is the lack of time. The site should live, it should constantly have new and interesting information. And it demands a lot of time. But I hope to cope with this problem.
To sum everything up I can say that I DO need my personal site and I will have it.