Start here: it's a nice 2-minute overview.
An excellent overview of what apprencticeships involve. "Not your father's apprenticeship" is one main point.
Great summary of how to figure out if an apprenticeship is for you, and how to search for an appropriate position.
Washington State Labor & Industries is the definitive source for apprenticeship information. Search for a program in state. Limit by county and field.
Often there are minimum standards beyond having high school diploma and being the age of 18 (some are open to 17 year olds). These programs--the sectors and training vary--will help young adults be prepared to enter an apprenticeship program.
This organization is just what it sounds like.
User-friendly site on the why, what, do, and how of apprenticeships. Has extensive links to further resources and a parent section with great information.