How are lenses and lens elements made? Also how are the lens elements and groups etc. arranged in the lens?
In regards to the glass, are the elements ground, moulded or are there other techniques that manufacturer's use to make them?
The TV show "How It's Made" did a show about this subject once. You can find it on YouTube.
For Canon specific lenses, see the Canon Camera Museum Technology Hall - Virtual Lens Plant.
Nikon also has a page specifically about how they design/manufacture lenses, and their PGM mouldings.
Otherwise you can see here for alternate details: http://en.wikipedia.org/wiki/Camera_lens#Construction