What about some HappySad faux-Italo disco from Sally Shapiro?

And alternative modern classic Just Like Christmas from Low? Spectoresque sleigh bells aplenty.

One more. A rather beautiful choral effort from Anúna.

(and the Low CD above is fantastic)

Sadly never seem to appear on festive compilations:

T. Rex - Christmas Bop
Simon & Garfunkel - Silent Night
Kylie Minogue - Santa Baby
Zombina & The Skeletones - A Chainsaw For Christmas
Grandaddy - Alan Parsons In A Winter Wonderland
Bright Eyes - Blue Christmas
Low - Just Like Christmas
Johnny Cash - Hark! The Herald Angels Sing
Ron Sexsmith - Maybe This Christmas
The Ramones - Merry Christmas (I Don't Want To Fight Tonight)
The Flaming Lips - A Change At Christmas (Say It Isn't So)
Eels - Christmas Is Going To The Dogs
Julie London - I'd Like You For Christmas

some of them here:
http://open.spotify.com/user/badger_king/playlist/65rbyPLkWV6Mv7jiNbypp7

...but boy, Christmas Time (Don't let the bells end)by, ahem, The Darkness came on in the pub the other night and I adored it! And it wasn't the beer hearing either...help me.
btw Love your list Badge!

counts as obscure, here anyway. And I suppose it is only Christmassy because of when it was originally released. But the Maps version of Stay Another Day, pitched somewhere between Yazoo and Spiritualized, is luvverly anyway.

The Boomtown Rats live version of Do They Know... It works well as a band song IMHO. (Special nod to the drummer's b vox)

I heard this the other day. Quite jazzy, mellow. Almost spiritual.. Christmas carols like you've never heard. Ok, it's not pop. www.jazzchristmas.co.uk

I'm no great lover of "folk" music generally, but Kate Rusby's Sweet Bells - released last year - is a lovely Christmas album.

I'd also support those recommending Low's Just Like Christmas, but I'd go a bit further and recommend the whole album, called with beautiful simplicity, or stunning unoriginality, Christmas.

The Manic Street Preachers' Ghost of Christmas Past, released via download only a couple of years ago, is a fantastic glam-styled, old-fashioned Christmas song.

Finally, I never get tired of hearing Davitt Sigerson's It's A Big Country, as thoughtfully included on a Word CD some time ago.

Christmas Evermore

Probably not that obscure, but surely the only Christmas song where Santa comes down the back passage rather than the traditional chimney.

Dido - yes, really

Sarah McLachlan

And, er, Guster

All to be found on an absolute gem of a festive compilation, which gets played as much as the aforementioned Low album:

http://www.amazon.co.uk/Winters-Night-Best-Nettwerk-Christmas/dp/B0002S9...

My favourite. I have it on an old A & M 7" single and have never seen it on a CD or Christmas compilation.

Epping Forest based anarcho hippies tell us why Christmas is a bad thing. Truly abominable. Possibly never played on the radio anywhere, ever.

http://www.last.fm/music/Crass/_/Merry+Crassmas+-+Side+A

It's hardly obscure, but I need to yet again make a case for this as the greatest Christmas song; because it dares to articulate, not merely in a 'bah humbug' kind of way, that Christmas can be a tremendously sad or difficult time for many people for various reasons. And - and this is more true today than ever - in many cultures, you simply cannot escape it even if you want to; and to even feel like you want to labels you curmudgeonly and joyless.

And yes, it is on the compilations etc, but doesn't get played quite as much of some of the others