@treebeard uNav, album, alarm clock,and utlnwallet (for Bitcoin) added above.
That's all folks. None of the other apps I have installed seem to have a url dispatcher command configured.
I had a look through the url dispatcher source code very briefly and it seems to support both these mechanisms:
<command>:// (two slashes)
<appid>:/// (three slashes)
so more apps may be dispatchable, but that's as much as I know.