I just wanted to add a few points...
1) For those who were looking at the percentage of LLC's which were pierced does not tell you how effective they are. It is entirely dependent on your state's laws, entity structure, and adherence to corporate formalities.
2) I dont think anyone would suggest having an LLC instead of insurance. You should have both imo. Another problem with sole reliance on insurance companies is their frequent refusal to pay claims, then requiring you to deal with two lawsuits, one to defend yourself, then another to sue the ins co.
3) Corporate entities also provide additional tax sheltering benefits.
4) Provide vehicles for protecting & transferring wealth to family.
5) Provide protection of your investment assets from personal lawsuit (You are sued from an automobile accident).
6) Provide privacy (though not complete I must add).