The most unique feature of NESticle was probably the menu option "Pentium Crash". Clicking on it froze your computer. I know that first hand :-)

https://en.wikipedia.org/wiki/Pentium_F00F_bug

The author of NESticle sure had a weird sense of humor, which is probably why it is such a loved application!Besides the ability to relive your childhood by playing pirated roms :-)