There are two main categories that budgies fall into, and a fairly long list of sub-categories.  The two main categories are Normal and Opaline.  The sub-categories include Spangle, Dominant and Recessive Pied, Crested, etc... Its an extensive list that I will add to eventually.

Now for some get there quick buttons...

I've put Cinnamon on its own here because I'm not really sure where it should be.  It is possible to have a Cinnamon Normal, or a Cinnamon Opaline.  It is also just as feasible that any of the subcategories could be a Cinnamon

The subcategories can be split into two further categories according to their mode of inheritance DOMINANT and RECESSIVE

Dominant

Recessive

Does anyone have some information and photos of the Black Face ? I've read about it but never seen one.

Normal

A normal budgie has basically (colour aside) the same markings as a wild budgie.

For the record this is the first budgie that I ever bred.  His name is Pete.  For the observant ones that have noted the ring colour, yes he was hatched in 1999.

A normal is the easiest bird to identify, you will note on the picture the zebra markings on the wings continue right up the back of the head.  The black markings remain the same for green birds, just replace the white areas with yellow and the blue with green.

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Opaline

Cinnamon

As I think I said somewhere before Cinnamons can come in many varieties.  The basic theory of a cinnamon is the replacement of black colouration (or trimming if you prefer) with brown.  Its as simple as that!