The Object Assembler Add-on for blender is a pretty fantastic idea. You can build a larger model from a library of smaller predefined model parts, allowing you to snap together pieces with automatic alignment easily and quickly.

Object Assembler is a free addon for Blender to quickly and easily assemble predefined models with automatic alignment

You can create and use your own model libraries for the Object Assembler, and those “parts” can be anything really, from meshes of course, to lamps, materials, text, actions, armatures, force fields, or latices and the like. You can also download complete, cycles ready models from the Object Assembler Model Library.

Object Assembler is free, and to find out more, you can check out the Object Assembler page over at Empty Graphics here. [via blendernation]