I used to love soloing old raids. It was fun trying to figure out ways to beat the content. For example, C'thun could only be soloed in a very specific manner. :
WoD Beta - Wiped trying to Solo ICC 25m Normal!!! - YouTube
Portal Jockey (ICC 25 Achievement) Duo MoP - YouTube
World of Warcraft Nostalgia: Back To Icecrown Citadel - Ep. 13! (Solo 25 Heroic)
I never played enough to do Heroic ICC when current. Now that I can solo it I finally have my favorite set of all time. : wow
Fury Warrior Solo Gunship ICC 25 Man by Wild fighter