Digital simulation CAD product sold by COMPANY: Mentor Graphics. Available for Windows and Unix. http://www.model.com
Modelsim is a fantastic digital simulator for both Verilog and VHDL hardware description languages. It has used TCL scripting since before TCL was popular. While the Personal Edition (PE) only supports TCL, the SE and EE versions actually permit TK gui elements to be used.
Mentor Graphic's Leonardo Spectrum Logic synthesis tools also provide TCL scripting in their Level 3 version.