Solid Software by Shari Lawrence Pfleeger, Les Hatton and Charles C. Howell, Prentice Hall PTR, 2002
AM While intended for product and project managers it offers a nice overview of various techniques to develop reliable software. It has fairly little to do with Tcl as such, except that does mention Tcl/Tk as an outstanding tool:
Today, TCL/TK is widely used for a variety of tasks, including test automation, portable user interfaces, and portable TCP/IP applications, TCL/TK continues to go from strength to strength. Its tool-building architecture encourages the easy production of portable tools, both throwaway and longer-use. Thousands of developers around the world contribute continually, and the tool continues to grow.