Frequency by Product - One time, Monthly Quarterly etc.
Need to be able to forecast revenues by product. Add a field for frequency on each product line. Allow user to choose each product as: one time, weekly, bi-weekly, semi-monthly, monthly, quarterly, annually, and ideally custom frequency like every X weeks, every X months.
While you're at it allowing each product to have a default frequency makes sense too.
Also, for subscription based revenue I would want the option to see the ongoing subscription value exclusive of one time setup fees as the deal value and the ability to toggle between annual value and monthly value.