Disc Priest + Hunter works out. I use my DP with 3 Hunters in tow, 2xBMs and 1xMM. I've cleared alot of dungeons at and around level for them, but haven't made it out of Outland yet. I box 4, but that duo is a good one too. You've got a dedicated healer, dps, and simi-tank. Same principal with a DP+Lock, or DK + Dp in tow healing. Pally tank and Priest healer might work out too.