http://klaxon.uiui.net/celeb/
On the left sidebar, third box down, there is a listing of the types of Japanese celebs. There are idols, musicians, actors/actresses, journalists, politicians, and even AV stars.
Even Ichikawa Yui has her own blog..
With a few exceptions, most of these are lesser known celebs, but it's cool nonetheless. And, most blogs are hosted at places like yaplog.jp and livedoor.jp, which are actual blogging sites that anyone can sign up for.
