This website has kanji practice questions regarding kanji -> kana and vice versa, yojijukugo, radicals, antonyms, and synonyms.
It's sorted by school levels so there should be something for everyone. Note that the site is aimed at Japanese people practicing for the Kanji Kentei (a comprehensive kanji test), so sometimes you'll run into words that are common for native speakers, but rare for foreign learners.
It's sorted by school levels so there should be something for everyone. Note that the site is aimed at Japanese people practicing for the Kanji Kentei (a comprehensive kanji test), so sometimes you'll run into words that are common for native speakers, but rare for foreign learners.