This week Bethesda announced they will release the G.E.C.K., which is the Fallout 3 equivalent of the Elder Scrolls Construction Set, but even without a construction set, there are still some great addons already out. Fileplanet put out a great pack of addons already out with some amazing additions, such as:
* Continue play after completing main quest(NEW)
* Interactive Flash and PDF maps of the Fallout 3 world(NEW)
* Mod removing Level Cap at 20 and Skill cap at 100.
* EXP and level up reducing mods.
* Pip3000 UI mods and different colored skin models.
* Weapons and character stat balancing mods.
* Exciting Power Armor skins.
* Cool characters like Chuck Norris and Doomsday Wasteland Queen.
* New weapons and hi-res weapon textures
* Hi-Res monster skins.
* Different uniforms and outfits.
* New game music and sounds
http://www.fileplanet.com/194521/190000/fileinfo/Fallout-3---Fileplanet-Addon-Pack-v1.5I'm really excited about the first addition, because I for one thought it was amazingly gay that the game just straight up ended after the main quest was over.