With just three years of Reston residency, Susan Merk has already been described as “indispensable,” “a powerhouse” and “instrumental.”  When Merk, a paralegal by trade, began to join several community organizations after moving to Reston, she discovered a need for her professional know-how. But it wasn’t for her paralegal experience. Instead, Merk has made it common practice to donate another highly sought after talent — that of a webmaster.  “Mostly, I do web sites for gratis,” said Merk. “I think it’s a good way to contribute.”