Osu! Sure it's a PC program, but it means a lot to us.
So there's a custom ouendan game out for the PC called Osu!. It's still early in development, and there are no official plans for a DS port.
However!
This is good news for any anybody thinking about making a DS custom ouendan, because there is a standardized file format, and because there's a very good editor included in Osu. So all that's left to do is to simply make a client that can read the osu files for the DS.
Maybe the next DS ouendan project won't disappear like the last one :)