Hmmmm. Just off the top of my head:
Omaha Beach from Medal of Honor: Allied Assault. Will always be awesome.
The Heat-inspired bank heist mission from GTAIV. Makes me super excited for the heists in V.
As far as bosses go, pretty much all of Dark Souls.
1/11 - Skull Fist
1/16 - Reel Big Fish?
1/18 - Mayhem
2/12 - You Blew It
2/19 - 1349