If you don't drive much and if you're a safe driver, you can save money with these pay-as-you-drive insurance plans. This Business Insider article
has a good overview of the popular plans. Unfortunately, many aren't available nationwide.
Some of the ones reviewed in the article include Progressive's Snapshot, State Farm's Drive Safe & Save and In-Drive, Allstate's Drive Wise, The Hartford's TrueLane, Travelers' IntelliDrive, Esurance's DriveSense, Safeco's Rewind and GMAC Insurance’s Low Mileage Discount.
A small insurer in Texas, MileMeter, used to offer big savings for low-mileage drivers. However, it looks like their business model had problems. MileMeter no longer exists as an auto insurance company.