Having gone through this before here's my input;
Crafters and Cville are both correct. You need insurance. I've worked with it and without it. With it is an expense you must budget for and can be a 'female dog' to find for a low-budget film with stunts involved. Without it is cheaper up front but ruinously expensive if anything goes wrong on your shoot. Here's a couple of links to get you started:
http://csicoverage.com/entertainment/film.htm
http://www.productioninsurance.com/
Be advised: though these and other company's do offer inexpensive short-term insurance packages for film & tv productions all bets are off when it comes to productions with stunts, weapons, pyrotechnics and gangsta rap themes (music videos). They won't cover any of these types of productions. You'll have to get separate insurance to cover those aspects. On average, stunt insurance starts covering production budgets of $300k which knocks out most of the people participating in these threads. However, there are brokers who will cover such things but you'll have to dig for them.
Another thing to consider; many facilities you may wish to use as locations will require you to have a minimum amount of insurance coverage. I've seen it as low as $300k, but the more high-profile the location the more you'll need to have.
When on a budget, short-term production insurance is the way to go. Just make sure the period of coverage encompasses the time needed prior to production to prep your locations / receive equipment and the time to get everything cleaned up, inspected and returned/signed off. For regular operational insurance that's a more 'interesting knot to untie.'
If your freelancing or running your biz out of your house, you still need insurance but you have to weigh the everyday costs versus the 'what if?' costs. Your house / rental insurance will not cover your equipment losses in the event of loss to theft or damage due to human activity or natural disaster. The tough part is finding an affordable package that will allow you to continue to work without sucking away money needed for so much other stuff. Again, if you decide to get your own facility of any size, most states/cities will require you to have business insurance in order to do so.
