My insurance agent is also my dad and when I started my business he helped me extensively to set up correct coverage. I have two policies that cover me. First, is a liability insurance policy that covers me in the event that a person gets injured on a shoot from anything that could be deemed my fault. I believe there is a $1,000,000 limit on that. Second my equipment, as others have stated, is an inland marine policy that covers my gear anywhere I use it. It also includes rental reimbursement and loss of income should I miss a shoot do to stolen or damaged gear. My current policy covers me up $15,000 of gear. All together my premiums are $60/mo, but I feel very secure with that level of coverage and in the grand scheme of things is not that much for the piece of mind I have.
I had a big claim last fall (dropped my D700 and 300mm f/2.8). The repair cost $1,700 total and I had a check from the insurance company for the full amount minus deductible in 48 hours. It was well worth it.
On a side note, the policy states they will replace unrepairable damaged equipment with like kind and quality equipment. If my D700 had been totalled in the fall they may have not paid for a brand new one, but perhaps a refurb. I don't know for sure. That may have been kind of dicy.
I hope that helps.
"Sometimes I do get to places just when God's ready to have somebody click the shutter." -Ansel Adams