The Colour Theory page features a infographic created by Seth Wilson which concisely explains all the need-to-know basics of colour theory in a visual, easy to read way. It includes info about the colour wheel, colour harmonies, tints, shades, tones, palettes & lots more! It is a truly invaluable resource if you want to learn more about how colours work together and how you can choose the right shades to make your colouring pages really effective.
Discover Colours links to a 'design wiki' by Canva, an online graphic design software. This is one of the most interesting and comprehensive sites I've found when looking for the meanings and associations of colours- simply click on a colour to find out where it originates from and colour combinations it works well with. Loads of unusual shades are included so it's perfect for colourists who own larger sets of pencils/markers and want to make use of those 'in-between' colours.
I hope you enjoy the new resources; let me know in the comments if they are helpful to you!