Here's a PC Magazine article that lists the editors' 75 favorite apps for the iPad
http://www.pcmag.com/article2/0,2817,2362574,00.asp
http://www.pcmag.com/article2/0,2817,2362574,00.asp
Motion X GPS
Topo Maps (the red icon)
NG World Atlas
CoordTrans- Coordinates translator
Topo Maps (tan and teal icon), which allows off-line map dowloads, like for navigating to the port at Baku on the Caspian Sea
A few favorites:
Knot Guide
Sp. Anywhere- Spanish translator
Photogene
Air Display
I'm on my 3rd Blackberry phone and they haven't even started to begin to come close to offering as many apps as Apple and others do for the iphone and the ipad.
I waited several years for RIM to do so, still like the phone but I ordered a 64g wifi/3G ipad last week from Verizon for $399.