IS

well lets see for starters you could use the mpc for beats, drumkits and audio snippets plus sequencing. use the sp for loops and sequence your loops and other audio with the mpc's sequencer, finally use your sp as an efx box for itself and the mpc, and extra finally use your sp as a digital multitrack recorder. record your vocals bass, guiatar mixdown to a stereo track and then use the wav converter to convert them to wav files in your computer and then burn a cd.

so sync up the mpc's midi-out to the sp-808s midi in
that way you can start and stop the machines at the same time. you'll play your beats on the mpc and your more organic sounds+vocals on the sp-808. when you are
done building your song you will record your mpc sequences to a track on the 808 and mix that track with your 808 tracks.