This site is terrific https://www.udemy.com/ !

The concept of the site is that people are "teachers" about something (ranging from subjects like learning a coding language, how to use a microwave, etc.) for upwards of $500 all the way to free classes.

I've purchased a couple classes about using Blender, the 3D animation program, and you really can find hidden gems. I'm taking a free Ruby class too! If you're bored or looking for some help learning something, I'd highly suggest looking at it. :D

Another site I love is http://tf3dm.com/

People upload their 3D models (there's a whole bunch of different file types - .obj, c4d, .lwo, .blend, etc.) on to the site for your use!

Some people allow you to use their models in mods, games, etc. Some are only for personal use, some are for commercial, etc.

On the site TF3DM, I made an account where I will be sharing my models! Yesterday I made a four leaf clover for the game Tabletop Simulator. If you'd like to use my model, here's a link

http://tf3dm.com/3d-model/four-leaf-clover-59646.html

It's in .obj format.

Much like the site TF3DM, This is probably its Russian Counter part, And has alot of models from Popular videos games ported unlike TF3DM. It features Weapons, Vehicles, Buildings. All that you need for your Porting, Animating, or Modding project needs!

http://p3dm.ru/

The formats are commonly in .OBJ and .MAX formats.

This site you can't beat ;3;

http://www.models-resource.com/

It's where I've been getting my models to put into Tabletop Simulator. All the models there are ripped directly from a variety of games, are free to use in mods (most require credit to the person who ripped the models), and are in .obj format! It's a fantastic site.

If you went to the model site, you'll see that the creators also have websites dedicated to Sprites, Textures, and Sounds.

http://www.textures-resource.com/

http://www.spriters-resource.com/

http://www.sounds-resource.com/

Useful, right! c:

There's this guy on youtube who uploaded all voices + weapon noises from Team Fortress 2 and Counter Strike; Global Offensive.

The download link he provides is mediafire, I think, or you can alwayse use a site to download the youtube video. Helpful if you want to make a voice over mod using a voice from Team Fortress or something :D

https://www.youtube.com/user/Darkrai64/videos

When I was modding for Postal 2, I would use this site to download youtube videos

http://en.savefrom.net/

I didn't download their custom program, ignore that, I just used the download where you can put the link in the box :D It always worked well for me, though you'll have to find a different site to convert things to different formats, like .ogg format.