Ask HN: Anyone use Insurance to cover Legal Liabilities?

Does anyone have experience with or advise getting insurance to cover the liability of potentially getting sued? Would General or Professional Liability or even IP liability insurance cover all the legal costs? I'm thinking that insurance in addition to corporate structure is a way of establishing a known cost as a way of handling the unknown (but significant) risks of potential suits -- not that I have any now or even in the foreseeable future, but I'm scared to death that after we start getting traction, some disgruntled client or some random schmoe will cause trouble, or some random patent troll will surface. It's a crazy litigious world out there and legal fees alone can kill a startup.