REJOICE PC Fallout 3 players! It is only a matter of time before some clever modders (hopefully including yours truly) start releasing the goods with new content. You can find info about the GECK in the quote and the link goes directly to the official BethSoft download page for the applet.

NOTE: Also check the related links. I'll add the link to the official wiki/tutorial page.. just in case: http://geck.bethsoft.com/index.php/Main_Page

The G.E.C.K. provides the community with tools that will allow players to expand the game any way they wish. Users 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.

Daigoji_Gai via fallout.bethsoft.com »