So, these were the ideas we came up with while playing. There will be two barbarian specs and two wizard specs, but only one WD because my other friend is kind of a jerk (kidding).
BarbarianBarbarian: Full Fury Tank BuildThe idea of this build is to use the passive of 25% damage with full fury to maintain that (notice, there are no fury spenders) damage buff and to avoid damage as much as possible. Taunt, ignore pain, a huge area stun and both the armor buff shout and the damage reduction debuff on enemies for keeping damage low and survival relatively high. We also think this build would excel with a healing monk.
Barbarian: Insane Earthquake BuildThis build is for creating a high damage earthquake build. With everything active, every 2 minutes you can pull off a 195% damage increase to your earthquake, which does 2000% weapon damage over 8 seconds - with the damage buffs from yourself alone, it is equivalent to nearly 6000% damage. With buffs from others (Wizard's Slow Time, Fetish Dance and Hex from Witch Doctor, and the Monk's healing affect of increasing damage, or the Demons Hunter's Marked for Death) you would be at 8000% weapon damage. The drawback, of course, is that after that small window passes, you are semi-toothless until they come back up.
WizardWizard: Exploding BubbleThis is a pretty offensively minded spec. Familiar could easily be replaced by teleport or diamond skin if I am lacking survivability, but the idea is to again stack damage buffs to make very powerful meteors. Flash of Insight is the central idea - proc that from electrocute and then drop Slow Time on a large group, then drop Meteor on top of them. Archon is both offensive and defensive - it has 3 attacks that each do 1000% weapon damage, so they would stack well with what's there, but also it would fare well as an "oh shi-" button.
Wizard: No Signature SpellSame idea as above, except without a signature spell. This is only possible if your arcane power generation is equal or greater to 20 a second. You can then cast Ray of Frost (or Disintegrate) and essentially never lose Arcane Power. You might have to spend some time running around to generate, but critical mass would hopefully be happening often and allow you to drop into archon frequently (or at least, with more frequency). This build is actually more defensively minded as well - some abilities could easily be dropped in favor of others (such as teleport).
MonkMonk Utility SpecThis would be the monk spec I would want to play with my buddy's earthquake or fury barb. Pull everything in, stun, taunt with ignore pain, monk heals for the damage buff, crippling wave or cleave to slow everything, drop slow time and a meteor on the group, and boom, lots of dead stuff. Also a nice 35% damage decrease for the enemy, as well as a damage buff for everyone - that can be swapped with other useful mantras.
Witch DoctorWitch Doctor PetlessAn idea I came up with after my friend lamented that he wanted to play a WD but didn't care for the pets. There are other ways to go but this looks fun - you turn enemies into chickens, throw toads and bears at them, and have a pretty heavy damage aoe every so often that has its cooldown reduced every time something dies nearby. I think this build looks really fun and might be trying it someday - after my wizard archons everything to death.
What are your spec ideas?