Although it’s not sheet music, I suggest you check out Ubizmo’s YouTube Channel to see the type of stuff that can be done with whistle (and ocarina).
So, I’m throwing down the gauntlet…
I challenge you to do a remake of “Dream Weaver” (In E) on whistle now instead of ocarina. 
<post it on YouTube soon!>
Hmmm…I think I’d do it in the same key as the ocarina cover, which was D. I was playing along last night and it really doesn’t sound half bad on the whistle.
Ubizmo
Yah, but then you won’t have the G#. 
(besides, E is the original key…)
EDIT: I’d love to hear it in either key, I’m just bustin’ yah. 
Thank you everyone for your replies!
I found a book online that looked fun - and had a review from our very own D. Wisley. Here’s the link.
http://www.amazon.com/Whistle-Around-World-Penny-Tin/dp/0825603420/ref=sr_1_2?ie=UTF8&s=books&qid=1288040146&sr=8-2
We’ll see how it goes. 
-S
Dave Mallinson does a series of tune books of traditional music from all the main countries of the British Isles as well as North America & France
Check his online store at http://www.mally.com/index.asp Select “Tunebooks by genre” link at the top.
I have his set of English session tune books as well as Pauline Cato’s Northumbrian Choice.
Those who play mainly Irish will probably find a number of tunes that you already know in these books because there is a fair amount of overlap in repertoire between the various parts of the British Isles. The difference is in the way the tunes are played.
Nevertheless, I am sure you will find quite a selection of new tunes.
Also check the EFDSS website http://folkshop.efdss.org/
They have a selection of books of traditional tunes, mainly English - They are, after all, the English Folk Dance and Song Society.
Stumbled onto this Chinese tunes in ABC notation.
http://abcnotation.com/searchTunes?q=china&f=c&o=a&s=0
To bad there is not any recordings real performers.
That Whistle Around the World book sounds interesting.
There was a teacher at the 2010 Folk College gathering (Huntingdon, PA), Gordon Bonnet, who has self published two volumes of Balkan tunes that he collected in the field, throughout Eastern Europe. They’re really nice. $15 for each volume, and worth every penny. You’ll have to contact him privately for the books, as I think he only sells them locally (Ithaca area).
Here’s his web site: http://www.cbgb-arts.com (yes, it’s primarily there to promote his visual art, but if you visit the Alize link, it’ll take you to his band.
Paul Oorts has transcribed a large collection of Breton (and Belgium I believe) tunes that are taken from, of all things, dance books collected by carillon players! It seems the carillon was the only instrument available for making music that could be heard well for dancing. In any case it is an interesting collection and even includes some transcriptions of French harpsichord masters.
Go to
http://www.pauloorts.com/at-play
and you can download the whole thing as pdf files!!! (and a text file with intro and indices).
Good stuff at now cost.
I have loads of books of non-ITM music.
Around 20 hymnals covering all the major US Christian denominations.
Perhaps 50 or so books of Scottish Highland Bagpipe music.
A book of Disney tunes, books of Bulgarian tunes, books of Baroque music, a book of fife & drum tunes, who knows what else.
One reason I collect music books is because you never know what somebody will request for a funeral or wedding.
There are indeed plenty of books of non-Irish tunes - apart from manifold on-line resources, ABC and other. Books of English, Welsh, Scottish, French (Massif Central), Breton tunes are relatively readily available.
There is a lot of traditional Swedish folk music here at FolkWiki. Plus you get pdf and midi, so you can hear the tune while reading the sheet music. Great for me as I’m only barely note literate. Though the place may be hard to navigate if your swedish is rusty, I suppose 