The Android market is starting to pick up for aviation now.

It is hard to find solid reviews on the products, but I think avilutions software is the top notch at the moment and only costs around $35 a year and includes geo-referenced approach plates.

Naviator I used the trial of and it was nice, but costs something around $75 a year on top of a monthly charge for Seattle Avionics geo-ref plates.

You can also use FlyPlan Mobile which is an AOPA design.

Personally, I choose Av for the price, ease of use, constant updates, and is very affordable.

None of the apps are on foreflights level but they don't cost $300 a year either. Also you don't need to buy an iPad. I use a Nexus 7 as well and I like it so much better than an iPad.

Avilution also has a pretty sweet app called SkyTracker. Go out for a flight and it tracks your entire route across a map in 3d. If you do aerobatics it should look neat, and can critique your maneuvers!