I'm looking for the best mods that add more things, and/or improve Megaton WITHOUT causing NPC routes to become messed up. I am having a blast with this game...and I just started playing it yesterday!
I like http://www.fallout3nexus.com/downloads/file.php?id=11710 and http://www.fallout3nexus.com/downloads/file.php?id=11035 to add more life and http://www.fallout3nexus.com/downloads/file.php?id=12037 for a new place to buy weapons and ammo. It has a few quests to obtain the new weapons.