Some thoughts:
Hash Table Syntax in Common Lisp (30 January 2009)
Options Trading 1: Buying Options (17 August 2009)
Options Trading 2: Selling Calls (18 August 2009)
Options Trading 3: Selling Puts (23 December 2009)
Options Trading 4: Modelling Options in Code (26 December 2009)
Options Trading 5: Graphing Options (8 January 2010)