They used to be notorious for frivolous lawsuits. I personally found it amusing how badly they got played by Beats, as documented at http://gizmodo.com/5981823/beat-by-dre-the-inside-story-of-h... and elsewhere.

My personal favorite example of absurd litigation was their threat to sue Blue Jeans Cable, documented at http://www.bluejeanscable.com/legal/mcp/. The response from Blue Jeans is seriously awesome.