This is our favorite 3D modeling tool. You can even make complete games with blender. They have a build in 3D engine and physics engine (bullet)

Check it out here: www.blender.org

Find tutorials here: Blender tutorials

I know. Everybody loves Photoshop. But please give the Gimp a try. When you get used to it it is really nice. Also lots of tutorials are available on the net.

Find it here: www.gimp.org

Microsoft took over Caligari in 2008 and gives away Truespace for free.

Check it out here: www.caligari.com

I think this is the only good alternative to illustrator.

Their website: inkscape.org

You really like Photoshop? Well maybe this can be a good alternative. It looks just like Photoshop. 2 versions are available. One is free the other is about 30€ (so allot cheaper then Photoshop)

Find it here: www.artweaver.de