These are the 2 sites that I use:
http://www.translation-services-usa.com/japanese.php – this site does not run as quickly and requires smaller fragments of the text to be able to translate, but I find it gives a better translation of what is being said.
http://babelfish.yahoo.com/ – this site will translate large sections of text but seems to give less accurate translations.
Having said that, Japanese text on Shogi-sites tend to use Shogi-terms that may not correctly translate on these service anyway. However those terms are limited in number and I try to mention those in both English and Japanese on my site (ie., edge pawn or hashi-fu (端歩), Forking king and Rook =(王手飛車 or oute-bisya) Sorry, for the last two years, I recognized I am not consistent in the way I explain the word)