Aerial photos (and even maps) aren't that good for theiving/exploring as you can't really get the "lie of the land". A smidge of green on the computer screen can in real life be 50metres of impassible gourse
BTW flashearth.com is useful aswell, used to be handy as it included google AND m/s, not anymore unfortunatly
None of the free aerial photography on the internet comes any closer than half a mile of my house, not sure if this is a good or a bad thing (my house isn't normally visible from the road )