Here are my favorites (in no particular order):

www.scifijapan.com/articles/
The new kid on the block, and one of the best. One of the owners posts here regularly.

www.monsterzero.us/
I must confess, I don't go to the title page much at all. But the discussion forums are my main source of kaiju/Japanese SF news. Ya' gotta' join to even just lurk, however.

www.tohokingdom.com/
Another fun source. Encyclopedia style, with just about everything you'd wanna' know about Toho monster and SF movies (and non-SF).

www.tokyomonsters.com/
Jim Ballard's site is terrific, and has an extensive download-able English subtitles library for the region 2 discs (and some R1 that got 'em wrong!). Indispensable!
"How many cares one loses when one decides not to be something but to be someone"
-Coco Chanel