THEGUI is an universal front-end for many command-line programs (moreover my tools) which works on both Windows and Linux since uses the GTK library
It has been successfully tested also versus programs like Nmap and Netcat and many others.
It is also very easy to use and has tooltips so is enough to keep the mouse pointer over a button to know what it does
On Windows you need to install the GTK+ 2 Runtime Environment
Download: THEGUI 0.3