I'm trying to use my G1 as my GPS device when i go hiking. Since i will hit many spots outside of tower coverage, i am wondering if there is a way to download maps and save them to my phone, so that my GPS location will not be a blue dot amidst a sea of gray boxes. Is there any way for this? Google maps and AndNav both download stuff temporarily, correct? they won't show any maps if they can't locate Edge or 3G network.