Having a personal site gives quite a lot of advantages for teachers.

First, a personal site can be a tool which helps teachers and students work together more effectively. As an example, I can give the following situation. Any extra material that you give to your students as a hometask is to be printed out from your computer and copied. Copying takes much more time than just uploading the necessary information and publishing it on a site. So the high-priority problem of saving time which teachers constantly lack of is solved, never mind saving money on supplies.

Teachers and students work effectively when they exchange the necessary information quickly. Teachers can publish up-to-date news about classes, timetables, surgery classes, academic progress or backlog, etc. As for students, they have an opportunity to request any necessary information.

Second, present-day students learn more effectively using IT-technologies, and a personal site can be a e-learning centre providing students with links to interactive exercises, teaching videos, web-quests, presentations, etc.

Third, having a personal site describes you as an IT-competent teacher which is an extra credit in the process of teacher evaluation.

And finally, some words against having a personal site. It takes time, but it's worth it!