I would have acted upon the fact that a random group of ragtag dwarves were travelling to Erebor, then loitered over the mountain waiting for Smaug to emerge, after which I would snap his neck before he could even smell the outside air, thus saving Laketown from unnecessary destruction.
The Battle of Pelennor Fields. Eowyn and Merry may take down the Witch King, but I'm going after Gothmog!
The mini-battle where the Fellowship breaks. I wouldn't have let Boromir die. But, as a Hobbit, I probably wouldn't have been much use. :)
I would have acted upon the fact that a random group of ragtag dwarves were travelling to Erebor, then loitered over the mountain waiting for Smaug to emerge, after which I would snap his neck before he could even smell the outside air, thus saving Laketown from unnecessary destruction.