Some links, then a discussion:
libertarian marxism is. Or where it doesn't work vs. where it does in the simple form (where the government runs the banks and the military, worker managed firms run the rest of the economy -- for a good model of a worker managed firm think of a partnership or a law school -- both of which reflect the strengths and weaknesses of the process).
See small steel mills, some rail roads, etc.
But it requires ownership of private property and free markets to pull off.