Currently, my main account has an epiced out 70 hunter.. and then I have 4 additional accounts where my shaman reside.
I will definitely get them all to level (edit) 80, then level a deathknight on my hunter account.. so that I can have a heavy tank for instances at 80..

EPIC! Your thoughts on this matter? Any idea if there are any synergy openings for deathknight + elemshams?

My current situation is that I often have to search for a tank to do heroics with.. which I absolutely hate. The reason I started multiboxing was to never have to depend on anyone else to do the stuff I want, and now I depend on them to do heroics.. bleh! Really looking forward to pimping out a deathknight with tanking gear.