Paul Levine introduced MIDAS back in the 90's through a series of lessons. His original text is available here. In the past few years his work has been revived with a number of articles by Andrew Coles and David Hawkins. Some of our favorite articles are available from Technical Analysis of Stocks and Commodities:
Also, for a brief introduction to MIDAS, please see Midas Market Analysis.
Coles and Hawkins recently published a book, MIDAS Technical Analysis. Their work is highly recommended - it thoroughly covers theoretical and practical aspects.