One of the things I hoped to do from my N7 was making and receiving calls using Google Voice , since I already have a phone number setup through Google that's tied to my DroidX. Natively it can't be done since Google Voice wants to use POTS to connect, but I found Talkatone
which does the trick.
Basically Talkatone is an VoIP app that somehow links to your Google Voice account and allows you to make calls. Unfortuantely on the N7 it doesn't tie into Google Now so you can't say "Call Mom" and have it dial out, but as long as its' running you can dial out or receive calls using your Google Voice phone number. Also what's weird when I tested is when an incoming call comes in both my cell phone and N7 rang, and whichever one answered first got the call.
There are a few other apps in Google Play that do the same thing, but this has the best reviews and is the only one I tried. Also it's free, but it does have banner ad's. I'd gladly pay a few bucks to get rid of them, but thus far the free version is all they have.
So FYI if you want to have full phone capabilities using your N7.