I've buy the i.Trek Z1 from semsons yesturday with a cm929-s mount which is 360 degrees so it seems to be adequate for the n800 in horizontal mode.

My choice for this GPS is for the solar capacities (over 100hours with sun!), a quite good chipset (MTK-32channels) and a build-in data logger !
I will tell you more when I will have it.

There's also a thread specialised for GPS receiver for Mapper where you can find all you want :
http://www.internettablettalk.com/fo...ead.php?t=1970