I was spectating a game and saw a player dodge Ezreal's ultimate with Shaco's ultimate. I was just wondering what other ultimates you could dodge?
Pretty much anything. When you use it, you basically cease to exist for half a second. During this time, Shaco is completly invulnerable to any damage. So if you time it exactly right, you can even dodge targeted abilities, like Caitlyn's or Darius' ultimate. You also won't take damage from DoTs and persistant AoE attacks durning the duration, but this is less useful, because of the short duration of the effect - you will dodge one tick at most.
For other types of untargetability see: http://leagueoflegends.wikia.com/wiki/Untargetable