Links I Think Are Useful:

lainchan: An image board focused on cyberpunk and technology related content, frequently features interesting programming posts.

hackaday: A blog which contains many interesting hacks related to hardware and software.

archlinux: The archwiki is a very useful source of configuration/installation info for lots of linux software.

/r/prog on reddit: A subreddit containg lots of interesting programming news and posts.

/r/linux on reddit: A subreddit containg lots of interesting linux news and posts.

libgen: Books.

w3schools: I tend to look up lots of html css and js stuff here.

jsfiddle: A good place to demo/test simple web projects for yourself.

Geogebra: An online geometry utility.

Interactive Math Site List: A list of interactive math sites from the subreddit /r/math

List Of Free Online Math Resources: A list of free online math resources from the subreddit /r/math

GIMP: The GNU image manipulation program, a FOSS image editor.

Ardour: A FOSS digital audio workstation

LMMS: Another FOSS digital audio workstation

ThreeJS: A cool library/api fpr creating 3d graphics in the browser.

onlinesequencer.net: An online midi sequencer.

Vocaroo: A website for posting short audio clips/files.

Imgur: A website for posting and sharing images.

Soundcloud: A website for posting audio and music.