New in Wolfram Mathematica 6: Fully Automated Graph Layout  previous | next 
Lay Out Arbitrary Trees
Mathematica 6 has efficient algorithms for laying out any kind of tree.
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Click for copyable input
TreePlot[Table[

  i -> FromDigits[RotateRight[IntegerDigits[i, 2]], 2], {i, 0, 511}]]
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