not a collection, but a special event:
Cross Country http://www.salzkammergut-trophy.at/unicycle-pid1091
Downhill http://www.salzkammergut-trophy.at/unicycledownhill-pid1424
Also you could look at http://www.taste-of-mud.org/ (no events for 2014 yet), a european muni race series.
Other pages for german events I answered you here.