Celtic Tree Oracle
This is an oracle rather than a standard Tarot, and consists of 25 cards corresponding to letters in the Ogham runic script of the Romano-British period Celts. It's based on the idea of a symbolic Celtic "tree alphabet" (which I understand to be part genuine and part wishful thinking) in which each Ogham letter corresponds to a tree (or other aspect of nature such as the sea) and has particular symbolic meaning.
The artwork is delicate and attractive but not informative, since it consists mainly of drawings of trees rather than of what those trees represent. The system is runic and gnomic: the cards/trees have meanings like "Oracular and protective;" "Best in the fight;" "The spiral of the self" and so on. It should be excellent for looking at trends of good and bad fortune and the gods influencing human life: not so good for comparing career options or romantic prospects.
Even though the tree alphabet owes as much to Robert Graves as to serious archaeology, and the author claims Ogham to be much older than the strict historical evidence will support, if you want something genuinely "Celtic" this, including the obscure and delicate I-Ching-like interpretations, is much nearer the mark than a deck showing a lot of beefy men in plaids and pigtails.