Fallout 3 G.E.C.K. Released
The G.E.C.K. (Garden of Eden Creation Kit) offers a set of mod tools for users to create custom content for Fallout 3.
Check the G.E.C.K. wiki for instructions, help and tutorials.
Word is: “With the 8.47MB download, you can “create, modify, and edit any data for use with Fallout 3, from building landscapes, towns, and locations to writing dialogue, creating characters, weapons, creatures, and more.”