My WoW mage and Dragon Age Rogue were good choices. This year, I've been on a pretty big Iron Man kick, so I decided to build a medieval themed iron man suit of armor.
The armor parts were mostly done with craft foam. I had a chain mail coif already, so I built the pauldrons and mask to hook onto it.
The armor pieces were modified from Mk7 foam/pep files. The forearm guards were held on with elastic. I didn't even really sew the tabard as much as I cut a hole in a piece of cloth I had and tossed a belt around it.