My mages were flame specced for the Living Bomb, Dragon's Breath and such. Those are fun to play around with.

I also worked in an AoE round robin, that had four mages cast Arcane Explosion, and one cast Blast Wave. And it'd just cycle through each of the five mages. If I held a modifier down, all five would use Arcane Explosion.

Also, guarding towers in AV is fun as a mage team. Especially guarding horde towers. They enter the tent and bam, five dragon's breaths, followed by five cone of colds and then some arcane explosions.

That's pretty fun, but the mages are so squishy still.