Here are some links that you may find useful. I’m not affiliated in any way with these websites but they have helped me in the past so I want to share them.
This is a great website for Zbrush Sculptors and Modelers. There are many great free Zbrush kits and some amazing ones to buy as well. All you have to do is make a free account and you can start downloading your brushes.
bubbl is a web app where you can easily create a brainstorming “mind map” and save it to your account. Whether you are writing a story, designing a character, or brainstorming any random thing, bubbl is a good place to start.
CGRecord has tutorials for most 3D packages that out there and some Photoshop ones as well. Chances are if you’re looking for a tutorial for something CG, CGRecord has it.
CG Skies is a great resource if you are looking for HDR skies for your CG projects. They have free samples of their skies for download, still in a pretty high resolution. The free samples are for NON commercial use only so for commercial use you must purchase the skies. Files can be large and they have limited bandwidth, so please be respectful and download only what you need; no stockpiling of all their skies at once.
Codecademy is a great interactive way to learn various scripting languages. When I first started using Python I found it very helpful.
Here’s a test to see how well you can distinguish between different colours. That kind of information is very important for artists because knowing your colour bias can help you better understand what other people see.
Creative Crash is a multi-faceted community where you can find things such as tools, models, software, plug-ins, and more. There are free downloadable scripts and tools for Maya users- among many other helpful items.
Creatures in my head is a website by Andrew Bell. There are thousands of his random quirky creatures on here- great for inspiration or practice with sculpting.
Feng Zhu and FZD School of Design created Design Cinema- a series of in depth tutorials on design and illustration for film and matte painting. Follow the link to the most recent Design Cinema video, where there will also be a link to the YouTube page with over 80 more videos on the subject.
If you ever wanted to know how to make your own HDRI’s this is the place for you. HDRLabs has in-depth tutorials on the entire creation process of HDR images. If you are looking for free HDRI’s go to their Galleries page to view and download.
Lesterbanks has a sizable library of tutorials for every part of the CG pipeline. They also have other cool things like daily CG news and funny merchandise for CG professionals.
For those who like to script in Maya, Mel Wiki has a lot for you. It’s a large resource database for all things MEL. They’ve also added a lot of Python stuff there too, so I would suggest the Python users also take a look.
Compositors take note- Nuke is a powerful and complex program that has amazing potential. Nukepedia is full of useful information and tools to aid you in your Nuke endeavors.
p3d is a great tool for modelers and texture artists who want to show 3d assets on the internet. You can upload your models to share them interactively and even imbed them into websites.
Posemaniacs is a great website for human anatomy reference. There are hundreds of poses with muscle textures so you can see how the anatomy fits together. It’s useful reference for posing characters or sculpting human anatomy.
TurboSquid has countless downloadable 3D assets. You can download many of them for free or pay more for higher quality assets. Usage rights vary so make sure you keep it legal.
Free high-res stock photos that you can use for any purpose. They have 10 new photos every 10 days and they are under Creative Commons Zero license- which means you can use them for any application without giving attribution to the photographers or the website.
Video Copilot has a huge collection of plug-ins and tutorials for Adobe After Effects to achieve any effect you can imagine. Some third party plug-ins may be required but their tutorials are free to view.