How To Practice Art » A short but helpful comic.
The Etherington Brothers » Hundreds (literally) of tutorials on drawing.
Creating Pixel Art » A complete tutorial about the basics.
MiniBoss' Pixel Art Tutorials » Tutorials on making and animating pixel art.
Reference Angle » Rotate a 3D head to get reference photos of people at any angle.
Animal Photo References » Similar to above, but for animals.
Body Visualizer » Enter body measurements to generate a 3D model.
Visual Height Comparison » Enter measurements for height comparison.

Rhymer » Find rhymes for every word.
Classic Short Stories » Read short stories for free in your browser.
Archive of Portuguese Legends » Read Portuguese folk stories. Portuguese only.
Fantasy Worldbuilding Questions » An in-depth guide to creating worlds.

JapanDict » My favorite online dictionary.
JLPT Sensei » JLPT grammar explanations, vocabulary and kanji.
Tadoku » Find reading materials based on you JLPT level.
Verb Conjugation Guide » All verb conjugations explained in one article.

Floras » A ton of HTML codes for many different effects.
The Doll Archive » Many resources and helpful links.
CSS Layouts » Premade CSS codes to create many different site features.

Twine » Create text-based games with simple coding. Browser version available.
Freem » Download free japanese indie games.
Dave's Mapper » Create dungeon maps in browser.
Emofuri » Free animation program. Japanese only; see an English guide here.
Tiny Tools Directory » A comprehensive listing of small, free, or experimental tools.

The Forest » Visit a random website.
Picrew » Many character creators and dress-up games.
Google Feud » Guess the autocomplete searches.
Little Alchemy 2 » Combine elements to create new ones.
Explorable Explanations » Learn and explore different topics through interaction.