Hey I have only just got my octatrack and have been wondering the same thing. One of the first things i did was slave my maschine to the OT clock and run the audio back into the OT via a thru machine - worked great!
I have a few hardware synths and use Live as my main daw but have always found Lives external sequencing to be all over the place so I want to get a step up going where Live is slaved to the OT, with Maschine as a plugin in Live and have the OT sequence all my hardware synths. Then basically have the hardware audio running either through a mixer back into the OT or back into Live, not sure yet.
One thing is for sure though, love the OT! Midi clock is tight!