Just a little mod I leeched.
Some of the commands are:
/god on=godmode
/lava on=turns on lava by click(useful for griefing)
/selsize x (size)=sets the size of the lava ex 20=20 buckets size
/debug on=debug mode
/build on=break and build anywhere on screen
/give (item) (number)=give command Case Sensitive
/give TNT Cannon=Gives you a beautiful thing
/spawn2 (npc id) (quanity)=spawns mobs
/noclip on=noclip
/goblins (number)=Goblin invasion example /goblins 200 would make a goblin invasion with 200 goblins
/speed (number)=Changes ur walk speed
/invisible on=makes you invisible on multiplayer

Instructions:
Just put it in your main terraria folder where terraria.exe is I named it Terraria1 so it dosen't overwrite your original terraria.exe cuz it dosen't really matter as long as its in ur folder.
Virus scan:
http://virscan.org/report/acf3fd696e...329027b48.html