Hi there;
This is a quick list of programs and other stuff that is very usable for game programming which is offered up free of charge and free of royalties.
If you know a tool or other thing that is handy for game programmers, please don't hesitate to add it to this list. Nothing it hosted here, we only link to stuff.
Please note that some programs may be marked as 'Strong Copyleft'. This means that the license of that tool or product may require you to make the game you create free or to copy the license of the product you chose. The GPL is the most famous example of that. So I really recommend to check the licenses before using the stuff I link to.

3D Development tools
Anim8or
Art of Illusion
Blender
DeleD
DeleD Designer
Design WorkShop - Lite
FREE!ship
HME - Height Map editor
K-3D
LithUnwrap
Maplet
Metasequoia
Midnight Mesh Modeller
Now3D
QuArK - The Quake Army Knife
SlimShady Lightmapper for B3D
TerraGen´┐Ż
TextureWobbler
The Persistence of Vision Raytracer
Wings 3D

3D Models and Buildings
3D Export
Exchange 3D
Psionic

Audio Tools
Anvil Studio
Audacity
cfxr
Fami Tracker
Frinika
Kristal Audio Engine
LMMS - Linux MultiMedia Studio
ModPlug Tracker
Soliton
SoX
WinVorbis & Vorbix

BlitzMax tools and modules
Brucey`s Modules
Framework Assistant (for BlitzMax)
MiniB3D (for Blitzmax)
RottBott Studios
Tricky`s Modules
WxMax

Font Tools
Bitmap Font Builder
Bitmap Font Writer

Fonts
1001 Free Fonts
Absolute Font Archive
Acid Fonts
Da Font
Font Squirrel

Game Creators / Engines
Godot
Love2D
The OHRRPGCE

General Graphics
Clker - The online royalty free public domain clip art
Copyright-Free Photo Archive: Public Domain Photos and Images
DHD Multimedia Gallery
Free Clipart Now
Free Media
Free Sprites
i2ClipArt
Image After
Kelvin Shadewing
Morgue File
Open Clip Art
opengameart.org
Reiner`s Tilesets
Stock.xchng
WP Clip Art

Graphic Tools
Avi4Bmp
Color Pic
Cool Text - Logo Creator
FontText
Formati
Games Factory Pack
GIF Splitter
Graphics Gale
Image Magick
InfranView
Juicy Fonts
LazPaint
Maoi
Paint Studio
Paint.NET
PhotoPlus
Pikopixel (Mac)
Pinta
Pixel Art Studio
Seashore (for MacOS X)
The GIMP
The Wood Workshop
Trout
Ultimate Paint

GUI Tools
ZPaint

Icon Editors
GJ PIM
Ico2O
iConvert Icons Online
Img2icns (OS X)

Installers
Iceberg (for MAC)
Inno Setup
NullSoft Install System

Libraries
DevIL
Easy BMP - Cross Platform BMP library
Genesis 3D
IRRLICHT
MonoGame
OGRE 3D
Open Dynemic Engine

Music
Echo Blue Music
Free Music Archive
HRT Studios
InCompeTech - Royalty Free Music
Mark Sparling 70 day challenge
Nihilore
Ozzed.net
Sound Image

Packers
JCR6
UPX: Ultimate Packer for eXecutables

Programming Languages
BlitzBasic
Euphoria
Free Pascal
FreeBASIC
GLBasic
Go
Just BASIC
Python

Scripting
Lua
NIL
Squirrel

Showcase Sites
Game Jolt
itch.io

Sound Effects
Absolute Sound Effects Archive
Dr. Petter`s SFXR
Find Sounds
Kelvin Shadewing
LabChirp
PACDV Free Sound Effects
PacHD Free Sound Effects
Sound Image
Sound Jay
www.freesfx.co.uk

Source Editors
Eclipse
Geany
jEdit
Notepad++

Textures
Absolute Background Texture Archive
Absolute Cross
Free Media Goo
http://textures.forrest.cz/
Image After
Indezine
Lost & Taken
Mayang
TextureMate

Tile Editors
DAME
Mappy
Tile Studio
Tiled Map Editor

Tutorials
C-Unit DirectX Tutorials
Codecademy
Free license list
Jeroens Lua Guid
Kelvin Shadewing Squirrel Tutorials

Uncategorized
Heks
Kitty
Morduun Big List
Resource Hacker
RPG Toolkit
Tokamak
www.icsharpcode.net
XVI32 - Freeware Hex Editor

Web Promotion
Epocu - Gaming Crowdspeaking Platform

Webtools
Blue Griffon
Sourceforge