I'll second with Gomotron said, works for me too. One heal key for 4x LHW on the tank, if anyone else needs heals all the shammies chain heal, I don't bother trying to micromanage. It helps that my pally has several pieces of Ulduar 10 gear and one or two Naxx25 items, but all the shammies are in crafted/heroism badge/heroic 5-man gear (and all 5 started out with quest blues and crafted items). Don't be shy about wearing the leather resto druid or even cloth pieces that drop, they're better itemized in many cases for ele sham dps (haste/spell power is generally better than SP/crit/mp5).

Don't forget to drop resist totems -- 2nd boss in DTK for example, frost resist totem helps a lot with the healing, and nature resist helps with 2nd boss Gundrak. Also magma totems can get you around mechanics like the ice block the first boss in UK does. One shammy gets frozen, just have the rest drop magma and you're back to full strength very fast. Positioning matters too; most of them I leave the shams bunched up, but sometimes they need to be spread out.

In the PvE forum there's a thread with movies of a DK/4shammy team running all the heroics, these are excellent for tips on how to do each fight.