Many cool apps for the iPhone, but I really use this one! (you can run this from a PC also)
Type in MIKE in the search window for wacky results! ^^
Kanjiroushi Japanese dictionary includes all you need for studying japanese: Lists of hiraganas and Katakanas. A dictionary of the 1945 most common Japanese Kanji, 100 000 words and 40 000 sentences. Tests to train your knowledge of the kanji meaning, Hiragana and Katakana reading.
The name of this website, 過ん字労死(kanjiroushi), is a bad pun using 漢字 (kanji) which is the name of the signs and 過労死(karoushi) which means death by overworking.