I have personally checked all of the links listed below and to the best of my knowledge all offer free services. It may be necessary to register before being able to use said product but to the best of my knowledge there are no hidden costs or bills invloved.
P.S. all of the links below will open new tabs when selected. I didn't realise there was so much controversy attached to the target_blank function. I hope you can forgive me for using it in this case.
Game Engines and Editors
Unreal Engine 4 is a suite of integrated tools for game developers to design and build games, simulations, and visualizations.
Unity is a cross-platform game engine developed by Unity Technologies and used to develop video games for PC, consoles, mobile devices and websites.
As well as can be expected, there are literally tons and tons of tutorials covering pretty much everything you need to know about both of these superb programs. Below I have included just a few links to some of these tutorials. Have fun :)
208 extensive tutorials ranging from beginner to expert.
Lots and lots of Unreal tutorials as well as showcase reels.
100 great Unity3D tutorials covering a wide range of topics.
Wide range of Unity3D tutorials ranging from beginner to expert. Also lots of showcase reels made with Unity.
Concept / 2D Resource Sites
This really is a fantastic site and one of my all time favourite places to go. It is jammed pack with extremely talented and creative artists. If you are just looking for inspiration or want to post your work here, I can definitely recommend taking a look.
I don't think there are not many people left who have not heard of DeviantArt.com. This site is absolutely gigantic and offers everyone the opportunity of uploading and showcasing their image based work. There must literally be millions of images to search through. Highly recommended site.
Similar to DeviantArt, CG Society is a platform in which professionals or Artists of all levels have the opportunity of showcasing their work. I have found that Users here are very helpful and give tons of good objective advice regarding work posted. CG Society is an excellent site and is highly recommended.
Back in the day when I first started working as a texture artist, I would frequently visit good-tutorials in search of tutorials to help me improve my Photoshop skills, which it did. Since then the site has drastically expanded and now offers a vast amount of tutorials from 3ds Max to Photoshop and HTML. All in all, a great site well woth taking a look.
Fonts / Brushes
Brushlovers as the title suggests, offers a huge selection of high quality brushes. You can also find a great number of different styles, patterns, gradients and vectors. The site is very easy to navigate through and definitely gets a thumbs up from me.
1001freedownloads offers a gigantic number of great brushes, fonts, wallpapers, vectors, patterns and much much more. Everything listed here is free to use and download and is well worth taking a peek
1001fonts.com is a very nice, clean and professional looking site. The site is very easy to navigate through and offers a lot of very high quality fonts.
Fontspace has very nearly 28,000 fonts available for download. The site is also very easy to navigate through and I can thoroughly recommend having a look.
Simplythebest offer a wide range of different fonts. There is not too much one can say about it really, apart from that it is an excellent source for fonts and as the saying goes "Does what it says on the tin"
Game related Media
Gamasutra is a great site offering an insight into the world of game development. There are lots of articles from the studio developers themselves to artists, programmers and audio designers. There is also a jobs listing section as well as a section on Indie games. Basically a must for everyone working in or intereseted in computer game development.
Polycount is a great forum offering anyone interested in computer graphics or computer games the opportunity of browsing through a massive selection of different topics. These topics range from being able to showcase your 3D or 2D work to technical talk. There are also competitions to take part in as well as a jobs section to look through. Polycount is a very professional and well thought out site.
Sketchfab is a fantastic site for anyone wishing to showcase his or her CG related work. The great thing is, is that you can upload and view your 3D work in realtime i.e. rotate, zoom in and out and be able to explore your object(s). The site is very well designed and an absolute pleasure to use. If I had three thumbs, they would currently be in the up position.
3D Modeling / Sculpting
3DM3 is an extremely well designed and professional site offering a huge amount of free high quality tutorials and assets. Their tutorials cover every program and topic I know of ranging from modeling in Maya to Z-Brush and Blender3D. There is definitely something to find there for anyone interested in CG. The tutorials are either in written or video format. This site gets a thumbs up from me.
CG Masters is also a wondeful and professional site offering a lot of free tutorials. The tutorials cover a wide range of different topics mostly using Blender. Although I have never used Blender before, I have however looked at some of their tutorials and am very impressed at the quality. Definitely worth taking a look.
Texturing / Mapping
Antony Ward is the author of a great set of video tutorials covering the topic of texturing and mapping a 3D model. There are 14 videos in total covering all aspects of texturing including uvw mapping to creating the textures from scratch. Each video is very well done and Antony does an excellent job in explaining each step. Antony also has a YouTube channel with more tutorials which you can view by clicking on his name above.
Here you can find a very nice article on texturing written by Jeroen Maton. The article covers some important aspects of texturing such as what is a base material to looking at the importance of adding small details. All in all a very well written tutorial worth taking a look at.
Web and Design Resources
Freestock is a very handy site containing lots of links to other resource sites. The categories listed range from textures to code and pretty much everything which could be of interest to any budding artist or coder. The website is fairly new and as such is constantly being updated. Definitely worth taking a look.
Take me there