So far the biggest missing feature for my business is the inability to add billable expenses to an existing time invoice. I do IT support and often have a list of billable expenses that equals or exceeds my timesheet entries for a given project. 

Since I invoice on project completion but may have 2-6 weeks of time and materials to keep track of, it's better for me to enter expenses as I incur them rather than try to remember them all to attach to a standalone expense invoice. I also have a separate person responsible for invoicing, and she should be able to add all the associated expenses to the single project invoice after I enter them into the system.

I suggest a couple of ways to do this: 1. let us associate a billable expense with a project, and have the project invoice gather all unbilled expenses when it's created or 2. generate a list of all unbilled time and expenses and let us select which ones to add to an invoice.

As the billable expenses work now, I don't think we'll be able to use Zoho in the long-term.