Pixelarity / HTML5UP
Creations of @ajlkn, both Pixelarity and its freely-available partner site HTML5 Up provide a wealth of responsive, one-page website templates for use and modification. My HTML skills to date began with a few online tutorials, but mostly come from downloading, dissassembling, and attempting to understand various projects on Pixelarity. Indeed - many components of my site will look quite familiar to other users of this service! Additionaly, AJ) runs a website builder Carrd, so check his stuff out if you are also looking to learn!
Magic Toolbox provides a collection of image-focused tools such as Magic Scroll focusing on showcasing products on commercial sites. A special shout out to these guys - while their product is available for sale to use on commercial sites, they also provide free liscensing for personal use upon request!
FancyBoxThis is a tool by Fancy Apps for creating lightboxes; popup pages on your site for displaying photos at higher resolution, and short additional texts; such as this page!
This font includes a ton of icons for use on the web: I've used it here for email/twitter etc links.
MathJax makes it possible to display TeX equations inline on a website - for which I am forever grateful!