i have this, sort-of.
i only have one 'main' thought process, but there are several sub-threads running as well, which take over the main thought if they think of something good or if they turn relevant to the surroundings.
i have even noticed that these 'sub-threads' are able to percieve surroundings by themselves, so i can navigate a car while daydreaming, snapping out of it to just long enough and just in time to say 'turn right here' and then going back into the daydream uniterrupted...