I take it you want to look up kanji that you
can't read (you don't have furigana or roomaji
available). If so, you definitely want
Jim Breem's site:
http://www.csse.monash.edu.au/~jwb/cgi-bin/wwwjdic.cgi?1C
You can look up individual kanji and find stroke
diagrams and more, or you can look up 熟語(words).
Of course, if what you're really interested in is a
和英辞典 then you'll be happy with alc or yahoo.
http://dic.yahoo.co.jp/
http://www.alc.co.jp/
(alc's site is noisy--there's a dialog with a
和英・英和 button near the top)
You're really fast! thanks for the links, i think i'll use more Jim Breem's site, because is easy to find radicals. But everysite has its own diferential.