I know this is not Web 2.0! But we owe the HILT Group of Cardiff University a big vote of thanks for making their excellent handbook available free on the web, under Creative Commons. We don't need to keep on re-inventing the wheel (how often have we heard that!) yet too often we don't take advantage of other's experiences. This is NOT intended for anyone to read from cover to cover, but to refer to and get ideas.
Promoting to schools and students
Teaching aids (like their IL resource bank or Intute) Nints on Powerpoint, handouts
Evaluating your teaching
A whole host of supporting documents, lesson plans, feedback forms, marking schemes etc.
Really useful. Thank you again!