97 Things Every Programmer Should Know

O'Reilly is collecting wisdom to compile a list of "97 Things Every Programmer Should Know ". I'm sure there are contributions the Tcl community can offer, and perhaps get a little Tcl evangelism in there, too.

Perhaps someone could write one titled "Learn a dynamic language", with a fair and balanced argument for learning Tcl, Python, Ruby, etc., of course using Tcl and Tk as examples.