Piskel: For making pixel gifs; used to make my page header and site buttons
RV's free effects: Mouse and page effects; where I got the cursor sparkles!!
Pollcode: For adding polls to your website
Imood: Mood plug-in for your website, you'll need an account though
Tomanotchi: Tomagotchi but online. You can add them as a plug-in to your site and anyone can feed them for you, or you can just keep it in the tomanotchi website and care for it yourself if you don't have your own site
Mozilla Developer Network web docs: Very helpful, in-depth guides for HTML, CSS, and Javascript. Good refreshers/reference points, even if you know what you're doing.
Imgur: Free, easy-to-use image hosting site. Of course, I always suggest hosting any images on your site yourself, but oh well
Internet archive: A non-profit library of millions of free books, movies, software, music, websites, and more. I suggest archiving any sites you enjoy, so you can find them again even if they stop existing normally (I couldn't find a better way to word that)
Jukebox tutorial: