A lot of the stuff you'll hear in my tracks (especially Lofi Attitude) is me doing weird junk like this:
I make long reverbs and delays on aux busses. I put phasers and distortions on them. I have a lot of the instruments in the songs sending to these reverbs and delays. In ACID, the bussing will let you solo the aux busses, so I can hear what those channels sound like without hearing any of the dry signal (I guess you could just put this stuff on your instruments as insert effects at 100% wet too, but that could be annoying).
I play the song and if I hear anything cool in the aux busses, I just select a loop section and bounce that audio to wav and it is inserted right into my project. Now I have a nice clip of ambient sounding junk I can move around and put anywhere. I often put more effects on it and also even send that audio clip back into the aux reverb and delay busses from whence it came . I also do stuff like reversing the audio clip and pitching it down an octave or two can make some interesting sounds also.