Trackables in the form of GeoKrety (= Polish Geo Moles) are now integrated into OC UK.

Geokrety (sing.= Geokret) are based at http://geokrety.org/

Accounts are free -

GeoKrets are free, all you provide is the trackable item and a permanent label with the site URL and tracking code on.

Accounts are not obligatory to log GeoKrety into and out of caches.