I'll leave these here:

http://technet.microsoft.com/en-us/magazine/2007.03.vistakernel.aspx

http://www.tomshardware.com/reviews/windows-vista-superfetch-and-readyboostanalyzed,1532.html

But summary is this: SuperFetch does work, and turning it off slows down your machine.

Other third party tools might do similar things to SuperFetch. Some might be better, some might be worse.

Also, yes, it's possible to re-implement SuperFetch using entirely public APIs, but I can't see why you'd bother, given that SuperFetch is already there.