Alberto Cairo: Data journalism.
Andy Kirk: Data journalism.
Hans Rosling: Storytelling.
Edward Tufte: Classic principles.
Learn Excel: An In-Depth, Thorough Tutorial (With GIFs) by Ann K. Emery
My Online Training Hub by Mynda and Philip Tracey
ExcelJet by Dave Bruns
presentationmagazine.com/editable-maps: Downloadable US and state maps
colorbrewer2.org: Color advice for cartography
design-seeds.com: Color palettes for slides and charts
instant-eyedropper.com: Matching RGB codes
Font Squirrel: Download custom fonts to use in Word, PowerPoint, and more
WhatTheFont: When you’re trying to figure out the name of a font
p2i.eval.org: The Potent Presentations Initiative