Today’s free design resource responsive icon sets is designed and released as a freebie by Zlatko Najdenovski
This package contains 100 icons (AI, EPS, SVG, PSD) and the icons are based on 3 different grid sizes: 16×16, 32×32 and 64×64. The line weight always stays the same, 2px, which gives them a super-consistent look. Of course, since they are crafted as vector shapes, size is not a limiting factor.