It seems, based on several previews thus far, that every color will be getting a new Curse Aura in Commander 2013. Red has Curse of Chaos and green has Curse of Predation; and now, courtesy of the official card image gallery, we have seen the blue entry in the putative cycle. Meet Curse of Inertia:
Curse of Inertia 2U
Enchantment - Aura Curse (Uncommon)
Whenever a player attacks enchanted player with one or more creatures, that attacking player may tap or untap target permanent of his or her choice.
"As long as I pull the strings, you will dance." - Tezzeret
Similarly to Curse of Chaos and differently from Curse of Predation, this one only triggers once per combat phase. However, an ability that versatile is definitely enough encouragement to make everyone want to attack the player this is enchanting. It'll take out the strongest blocker; untap an artifact or land to activate its abilities again; give an attacker a form of vigilance for a turn; or any number of positive and negative things. That's a lot of extra uses for things and/or a lot of lost blocks, over time. If only this cost a little less, it might well see play in eternal formats.
What do you think of this tap-untapping blue Curse? Let me know in the comments.