from the Which-Door-would-He-Suggest? dept.
Computational nanoscientist Surendra Jain has written solvers for Sudoku,
Killer Sudoku, Samurai Sudoku, Calcudoku, Kakuro and many other
All are elegantly coded and very fast: for example, the "World's Hardest Sudoku" is solved in 0.05 seconds (on a 5 year old PC) and his Knight's Tour solver is an order of magnitude faster than this one.
The page (called "Classical Geek") has all source (in Fortran 90, one of the most popular languages in high-performance computing) as well as compilation and running instructions.