I use these sites (and many, many more) to cross check and verify. These are not in any particular order. I do not use any one site as the only source for identification. These are just helpful jumping off points. There are additional links to kiln websites under the pottery types on this blog, some of which have an English link (but most do not). You may also find my book reviews for books on Japanese pottery helpful. My library is growing. I have reference books in Japanese as well, that are not reveiwed, as they are not easily obtained outside of Japan.
HELPFUL SITES
This is a Japanese recycle internet shop that I use for styles, names and marks because the shopkeeper usually displays the box, mark and any identification papers. It is in Japanese but it might be fun to check it out.
Katsuragi ebay.
This site sells things from Japan. The site is machine translated English but is understandable. I use this as a reference. It is not 100% correct but often has the boxes and identification papers so I can check it out myself.
www.rikyucha.com
This site is in English,but ships from Japan. This deals mostly with tea ceremony utensils but has some other items. The potters name is given when known. Sometimes it shows the box and identification papers. You can sign up for the newsletter which adds interesting cultural tidbits.
http://Jisho.org
This is an on line Japanese dictionary. It requires some knowledge of Japanese but is a great asset for looking up kanji.
http://dictionaries.nihongoresources.com
I love this one because it shows different forms of Kanji that one may encounter reading marks, names and red hanko seals on boxes.
http://nippon-kichi.jp/
http://pukupukukichi.blogspot.com
http://shop.flimart.com/wa/goods/
http://www.imari.com/index.html
http://home.netyou.jp/77/k-okada2/yakimono.html
http://www.guinomiya.com
http://www5b.biglobe.ne.jp/~hayakaen/SOME-MENU.htm
https://sites.google.com/site/bandwresearch/home/imbande/printing-technique
http://www.h5.dion.ne.jp/~umebachi/zen.html
http://flyeschool.com/content/japanese-tea-bowl-feet