Awesome SVG

Reference

SVG 1.1 - the current standard
SVG 2.0 (draft) - the next version
W3C's SVG Page - home page of the group in charge of the standards
MDN - Mozilla's SVG reference, nicely hyperlinks and with lots of examples.
Wikipedia's SVG page - nice history and overview

Editors

Inkscape - open source, but no Mac support
Adobe Illustrator - powerful, but expensive, and no Linux support
Vecta.io - browser-based, looks promising
Sketch - commerical though not too expensive, but Mac-only

Conversion Tools

AutoTracer - convert from raster (JPEG, PNG, GIF) to SVG
svg2raster - convert from SVG to PNG
favicon - convert from SVG to ico. Works great for using an SVG emoji as a favicon.
iconizr - convert a collection of SVGs into a CSS icon kit
font-blast - convert an SVG font into individual SVGs
svg2android - convert to Android's VectorDrawable XML format
PDF to SVG - convert each page of a PDF to an SVG

Icons

svg-icon - includes icons from over 30 different sources.
GlyphSearch - similar to svg-icon though only 9 sources, but has a nice search function
The Noun Project - commercial, but boy do they have a lot of icons
icon section on awesome-design

Logos

LogoSear.ch is a great search engine just for logos, with the list of sources and alternatives.

Programming Libraries

D3.js - generate/manipulate SVGs from JavaScript. A great way to do graphs and diagrams: be sure to check out the gallery
SnapSVG - animate your SVGs with JavaScript
SVG-Edit - open-source JavaScript editor to embed in your app or website
SVG-Morpheus - morph from one icon to another

Compression

svgcleaner cli | GUI - compresses the most, and much faster than the others
SVGO cli | web - written in JavaScript and plugs into a whole bunch of different build tools.
scour - Python
nano

Can I Use

94.6% basic support - inside an embed or object element
94.5% HTML img
94.5% css background
94.5% inline in HTML5
93.9% filters
88.4% effects for HTML
88.0% SMIL animation - all except IE
18.4% favicons

Other Lists

css-tricks' Compendium of SVG Information - this site also a ton of great articles on using SVGs
Willian Justen's awesome-svg - not as curated as my awesome list, but still a ton a interesting links