Google Earth
This is the most fun you can have exploring the world from your desk.

Or explore your neighborhood. The ability to tilt, rotate, add 3-d terrain and buildings to the high-res maps Google already has is pretty damn cool.
If you don't want to go poking around yourself, check out Google Sightseeing, a blog dedicated to seeing the world, Google Maps style.
Thanks for reminding me of this great time waster. But doesn't it creep you out, just a little?
"Thanks for reminding me of this great time waster."
One of the founding principles of this site is to discover great time wasters for all of you, so, you're welcome.
As for it creeping me out? No, not really. If it showed the outside of my home in real time or almost real time, that would creep me out.