TkHelloWorld, by E.J. Bleeker, can be found at ftp://ftp.neosoft.com/pub/tcl/alcatel/code/tkHelloWorld.tar.gz.
The latest version of Tix, along with some other information, is located at http://www.xpi.com/tix/.
TkSound is written by Dan Ellis, and you can find out more about it at http://sound.media.mit.edu/~dpwe/tkSound.html.