Tabler Icons
550+ Highly customizable free SVG icons (MIT licence) https://github.com/tabler/tabler-icons
App Icon Template
… a free Photoshop resource that makes it easier for you to make icons. Edit a single object and it’ll automatically render out all the various sizes required on iOS & Android. Build in textures and colors make it easy to get started and the bundled actions make exporting a breeze.
The Icon Handbook | The Hickensian | Hicksdesign
(Here’s what it looks like)
The Icon Handbook
The Icon Handbook is a reference manual, how-to guide and coffee table 'showcase' in one. learn how to design icons for interfaces
Freebies Booth
Free design resources layered PSD, resizable vectors, PNG icons