https://en.wikipedia.org/wiki/Prompt_Global_Strike
https://en.wikipedia.org/wiki/Railgun
Thermobaric bombs are non-nuclear but do lots of damage. https://en.wikipedia.org/wiki/Thermobaric_weapon
These are big enough for most tasks: https://en.wikipedia.org/wiki/Massive_Ordnance_Penetrator
http://theaviationist.com/2012/02/12/mop/
Unrelated but cool if you like massive weapons:
https://en.wikipedia.org/wiki/Project_HARP https://en.wikipedia.org/wiki/Project_Babylon https://en.wikipedia.org/wiki/Schwerer_Gustav https://www.youtube.com/watch?v=XT5jo7aZzTw