Okay. Here's some stuff...
Engines
Delta 3D
http://www.delta3d.org - This is an open-source 3D gaming and simulation engine. It's free to use it any way you wish, and is designed to easily work with any other open-aource programming project.
Panda 3D
http://www.panda3d.org - This is the same engine that was used to create Disney's ToonTown. Disney then threw into the open-source ring. You can now download it for free to use in whatever you like. It has both Python and C++ bindings, supposedly the Python ones are almost as fast as the C++ ones.
Q Developer Network
http://qdn.qubesoft.com/index.php?main=home - This engine is cross-platform, but for the free version it can only be made for Windows and Linux. If you pay money, you can get it on OSX, FreeBSD, PS2, and Xbox. Other than the engine, it also comes with a pretty easy to use WYSIWYG scene editing tool.
The Nebula Device
http://www.nebuladevice.org/ - This is is open-source, multiplatform, and has API's and libraries to couple it with just abouty any scripting or programming language. Their idea is to make things simple, sweet, and powerful. Each release has shorter more efficient code than the last.
Tools
Blender
http://www.blender3d.org - This is an open-source 3d modelling program it has an intuitive interface and can make super high quality stuff.
Texporter
http://www.cuneytozdas.com/software/3dsmax/ - This is a plugin for 3DS Max that basically does what ultimate unwrap does.
Audacity
http://www.audacity.sourceforge.net - An open-source audio editing progam. It's easy to use and available on many, many platforms.
-Bryan-