I am not quite sure why they’ve done this, but I am amused. The Japan Weather Association’s website, tenki.jp, have included some social networking tools in their latest upgrade. You can twitter (hitokoto) about your weather, upload photos, add friends, ask questions.
Unfortunately, you can’t do anything useful like set a particular area forecast as your start page or even create bookmarks to the pages you use most frequently. Maybe in the next release.