An Introduction to Computer Science Using Scheme
gustavus.edu
gustavus.edu
Both HTDP and conabs inherit their methodologies from SICP. (in htdp you could even look at The Structure and Interpretation of the Computer Science Curriculum here http://www.cs.brown.edu/~sk/Publications/Papers/Published/ff...)
But it is worth to look at the same thing from different points of view. As Alan Kay says, it is worth 80 IQ points :)