There's also a new Kanon manga that started in the shounen manga magazine
Dragon AGE.
The manga started recently in Dragon AGE magazine, so no volumes are out yet.
Here's the title of the new Kanon manga:
ホントの想いは笑顔の向こう側に Kanon ～each regret of Kanon～
Honto no Omoi ha Egao no Mukou Gawa ni Kanon ～each regret of Kanon～
原作:Ｋｅｙ
作画:霜月絹鯊
Look here for a few images from the new Kanon manga:
http://www.fujimishobo.co.jp/pure/2006/06/post_75.php