Here are some links to some useful stuff.
We have planetary fact sheets from the nice people at NASA. Pretty smart folks when they remember to keep track of their units… Sorry. A bit of snide from my engineering-school days.
From the nice people who brought us the Bay of Pigs, here we have the CIA World Factbook. The format’s very stealable and it’s always good to have a ready supply of real-world stats on hand. And… you know… if you can’t trust the CIA who can you…?… Um, anyway…
Winchell Chung’s 3-D Starmaps site. This would definitely be in the, “Why the hell didn’t I already have a link to this?,” department.
Mostly this is just to help me build up a list of useful sites for my own purposes. If anyone else finds them helpful… Hey! Cool!