Being a fan of the old Realms of Choad books I always liked the idea that the Plaguebearers eternal curse was to count. Diseases, Nurglings, flies, what have you. They are also know as the Tallymen of Nurgle. I latched onto that idea for my Plague Marine warband, "The Tallymen". I'll include scraps of cloth hanging off of them with their tally marks. Still Plague Marines, but with a little more character. Here's my prototype:
