A Shallow Introduction to the K Programming Language - If you're in the spirit of the Pragmatic Programmers and want to learn a new programming language again, and are willing to take on something truly new and unusual, this is the right place. K can be considered a mixture of Mumps (the K-Tree reminds me strongly of it), APL, J, and functional languages. Wild, unreadable, extraordinary. Unfortunately, there is no native Mac OS-X version available, only Linux, Solaris, and Windows. Found at kuro5hin.org.