Easy - See You Again, Miley Cyrus
Fun - Perfect Strangers, Deep Purple
Intermediate - Living On A Prayer, Bon Jovi
Hard - Run To The Hills, Iron Maiden (that "galloping" drives me bonkers some days)
Insane - er.. The Real Me, The Who (only tried to play it once - after 30mins I got past bar 1 and gave up)
Edit: Or more recently for insane - Thunderhorse, Deathklok. It's that god damn galloping rhythm again except a hundred times faster. Arrrgggh!!!