Public-domain (CC0 1.0) collection of SVG icons and hexadecimal color codes for over 200 popular brands. Also includes CSS, LESS, SCSS with color variables, making it a sort of proto-framework.
The Open Share icon conveys the act of sharing by visually representing one hand passing an object to another hand, as in "pass it on" or "sharing". The icon also represents an "eye", as in "look at this".
Call it a badge, sticker, button, or whatever you'd like. Create yours below. Pick some colors, enter some text, and you'll get a button you can download for your site.