If you're not using the Sketcher in Drafting, MB3 (right click) on the view boundary and select Expand from the pulldown. You should now be able to snap to any valid geometry in that view. Keep in mind that any geometry you create will ONLY show up in that view (often called View Dependent geometry).
NX uses View and Model Dependent concepts for things like this. If you want the View Dependent geometry visible in other views, MB3 on the view, select View Dependent Edit and then select View to Model to move the geometry to the Modeling side. If you have ANYTHING associated (dimensions, view boundaries, etc.) to the View Dependent geometry, you will NOT be able to move it over to Modeling.
Tim Flater
NX Designer
NX 8.0.3.4
Win7 Pro x64 SP1
Intel Xeon 2.53 GHz 6GB RAM
NVIDIA Quadro 4000 2GB