this was my response to the "weird deck" thread so it pretty much applies here as well.
I guess my favorite "unusual" deck is the Tarocchi della Luna (pub. Atman - Laura Verzellesi), a 44 card deck which I've dubbed my Koyaanisqatsi Tarot.
it's a edgy and strangely illustrated set of mirror image Majors portraying both the natural state of existence and a frightening view of the Majors in their "reversed" states.
The artist has succeeded in vividly contrasting the destructive perversity of the Majors in a wanton state to the more reassuring and familiar Major Arcana archetypes we're all familiar with.
Death has ceased to be the crucible of change, the cycle has been disrupted, the natural order of life is out of control and the forces of Nature and the Cosmos are running amuk. It's like a butterfly effect of monstorous proportion.
The Sun consumes all with it's flame, the Hermit is lost, he has faltered and dropped his lantern, the Lion has triumphed bloodily in La Forza and so on.
this is one of the only decks that actually sends a shiver through me.
the book is in Italian without translation, but you don't need it, the images speak volumes and that's what a great tarot deck is supposed to do.
it's not the prettiest tarot art but I think it's profound.