Just do a search on google, something will pop up.

I know some mixing programs can do it, not sure which one it was though.

thats easy to figure out. find the first bass note. 99% of the time its a single note, not a chord or interval. once you found the first bass note, just plink some notes on a piano octave till you get that key. it has to be 1 of 7 notes including half steps. once you found it that is the root note and the entire song is usually based on a scale or chord starting from that note.

im not insulting the person that made this thread in anyway, as im in the same boat as him, but if hes asking for a program to figure out keying, i dont think he knows things such as octaves, intervals or chords, granted of course hes deffinitely heard of those terms as we all probably have, but i dont think he quite gets wat ur saying although im sure its great advice if he actually does get it (lol i dont quite, but i will) ill say this, when u click on the dj forums, theres like a whole thread, its like one of the first 3 or something threads (im not too sure im kinda mashed right now) and it has to do with key. if its not there but im sure it is, do a search on the forum, someone did a great "essay" if you will on it that was mounds of help for most people

ok i just checked, its actually the 2nd thread in the dj forum, good luck

Do like what ESMdjm600 said, but if you still want a program to do it, I've heard Mixmeister can do it well.