For your consideration ... the Vargo Titanium Mug / Pot which supposedly fits the 1 litre Nalgene Bottle. I understand that some were looking for a Nalgene Bottle Mug for canteen purposes.

http://www.backpackinglight.com/cgi-bin/backpackinglight/vargo_titanium_mug.html

Also:

Finally a new style Cap

http://www.humangear.com/capCAP.html

I have a Snow Peak Trek 700 titanium cooker that allows a 1L Nalgene to nest (albiet with an 1/8" or so of extra space).

Jim