physics scripts?

ok so i started poking in the game engine a few days ago, and after looking on youtube to see what people have done with i came across phymec’s videos which of course are totally epic. a little more digging i found threads and videos and meshpy and my favourite ; molecular physics script.

I was wondering how many of these different scripts are there that work so a total script newb ( ive only found out about scripts today ) use.
and is there an easy way to install and use them.
and if there are some around what would be peoples favourite’s to use