Personally:
Programming- Dark Basic Professional, easy, powerful and fun to use. Costs money
3D Modelling - Wings 3D- Free (I think wings is a more powerful modeller)
Animation/Import/Export - Milkshape 3D - $20
UVMapping - Lithunwrap (No longer supported by its maker, google it)
World Building - There's a really good free level editor in this months newsletter, or look for Evolved's lightmapper/world builder which is now free, you can find his website in his signature. Or get 3DWS
Terrain - I just use terrain I've made in my 3D modeller, however if you want terrain for free there's Terragen which can generate you a height map for advanced terrain, or just look in program announcements/Work in progress for people own made ones. Or get Ted.
"Cut down the gods if they stand in your way" - Hakamoto Tsunetomo