powerpoint slides talking about using Logic Circuits to implement AND, XOR Gates, etc. and also MUL, ADD, PLA...
http://cs.colgate.edu/faculty/nevison/cs201web/lectureNotes/transistorlogic.ppt

you can use "Simcir the circuit simulator" or xLogicCircuits to play with gates.
you can try to implement adder or Flip-Flop as follow: http://www.brunel.ac.uk/~castjjg/hndcfund/material/logic/part5.htm