Owatatsujin is a playable Taiko FLASH sim that has various songs from the game itself and also other songs that were notecharted by various people. But the graphics are... well, you'll see.
Here are some links
復活版！てらの太鼓のオワタツジン いそうのオワタツジン公開ページ 太鼓のオワタツジン サンダース＠ユウ自作譜面公開所
Search "owatatsujin" in Google or Yahoo to find more results
Some notable songs include:
Saitama2000 (reverse mode) - Listen to the hidden message!
Tenjiku2000
Mekadesu (renoted) - VERY fun
Gekkabijin (renoted) - O.O