I have recently bought boss RC-3 for practicing and laying out scratch ideas on the go,
but wonder if anybody use it beyond that? 

I mean I have workstations, sequencers, DAW and all these s$it but 
nothing is sipler and quicker like step on the pedal and rock on. 

I've got one of those, too. I had fun with it for about a day, jamming with myself and building up complicated percussion beds. That was in February. Since then it's sat on my desk, unused. I never found a practical application for it, either live or in the studio. I might dust it off if somebody comes up with an inspiring suggestion for this thread.

If you want to see masterful use of a looper, check out the link below.  It has amazed me every time I've watched it.  Remarkably, the young lady performing was just 17 years old at the time the video was made.
 
http://www.youtube.com/watch?v=izrL7pBdkaw

look at this guy..
http://www.youtube.com/watch?v=v5DoJx4Kmak&feature=relmfu

or here:
http://www.youtube.com/watch?v=A5VMQBmgEUg&feature=relmfu

besides what Dub is doing with this is also cool: 
http://www.youtube.com/watch?v=VdJV97y5h98