Uh a few come to mind:
Battles:
Alexander - (shit film, but) Battle of Gaugemela, brilliant set-piece
Battle of Britain - take your pick of the dogfights
Waterloo - pretty much the entire damned film
LotR - Siege of Minas Tirith/Battle of Pelennor Fields (actually, I watch it more for the music)
Fights:
Crouching Tiger Hidden Dragon - everyone harps on about the unarmed fight, but I prefer Michelle Yeoh's versatility with several different weapons near the end
Matrix Reloaded - Chateau
Sword of the Stranger - Luo-Lang (Rarou) vs Nanashi
Fearless - Jet Li vs Nidaime Nakamura Shidou