Blender is the open source software for 3D modeling, animation, rendering, post-production, interactive creation and playback.
# Revolutionary non-overlapping and non-blocking UI delivers unsurpassed workflow
# Flexible and fully configurable window layout with as many screen setups as you prefer
# Undo support on all levels
# Anti-aliased fonts with international translation support
# Windows for animation curves/keys, outliner, schematic scene diagram, generic node editing system, non-linear video sequence editing, character animation action editor, non-linear animation mixer, image/UV editing, file/image selection and file management
# A range of 3D object types including polygon meshes, NURBS surfaces, bezier and B-spline curves, metaballs, vector fonts (TrueType, PostScript, OpenType)
# Very fast Catmull-Clark subdivision surfaces with optimal iso-lines display and sharpness editing
# Full multiresolution sculpting capabilities with 2D bitmap/3D procedural brushes (Paint, Smooth, Pinch, Inflate, Grab) supporting symmetry
And much more.
64bit version here: http://download.blender.org/release/Blender2.74/ Available for all major operating systems under the GNU General Public License