I would very much like to start a repository/outpost of design ideas for folks to try out/recommend/review, etc.
Da Button Factory: web button maker - An incredibly simple way to make custom buttons!
https://www.canva.com/ - An amazing free resource, but can be affordably scaled to meet much of your design and publishing needs. A LOT of free content, images, templates, all downloadable.
Odincons 1.0 by Nhat Anh | Dribbble | Dribbble - This is 100% free shape icons
Icons - Material Design - "Material icons are delightful, beautifully crafted symbols for common actions and items. Download on desktop to use them in your digital products for Android, iOS, and web."