My insurance company wanted $5 a month to cover two bicycles as some kind of rider on my house insurance. They also wanted serial numbers and photos.
I declined the opportunity and went for locks (actually cable locks... so sure me!) instead. That was 5 years ago and I haven't had a bike stolen yet. I figure when it does, I'll probably be in a few dollars... especially considering that my main commuter only cost me $75 (although there are many upgrades.)