I have created one in Excel. I have a sheet formatted for individual shopping companies, and these all feed up to a "Total Sheet" which is summarized by company. I have included columns for my mileage, tolls/parking, and out of pocket costs, and I break down the payments into reimbursements and fees/bonus.
I have one sheet devoted to links and passwords which is alphabetic by company and I update this as I find new companies. There is a master blank sheet for new companies which I copy and insert in place, which then links to the total page. I could send you a blank copy if you'd like. My main emphasis is to track monies due to me, paid to me, and mileage/toll. I will have nice summary for my Schedule C at year end. If you are familiar with Excel, you can organize one yourself. Any system that gathers and summarizes the information will suffice. I just happen to like Excel.
Best of luck.
Sheila