Develop Microsoft Outlook Add-in For Calendar
This idea seems to be proposed every so often, every couple of years, and then seems to get shelved (yes, for a while now there has been the option to sync the schedule back to Outlook but that is counter productive, IMO).
I would like to consider the TSheets product/service for migrating away from a competing service but the deal breaker is proper integration with Outlook's calendar. Like so many, my business lives and dies on Outlook calendar, especially because it is so tightly integrating with emailing, due to its feature rich calendaring capabilities.
I suggest developing a Microsoft Outlook add-in that can scrape, at the least: date, hours (based on start/end), keyed in billable/non-billable, keyed in customer and keyed in service item data, for ultimately pushing to Quickbooks. What happens in the middle is almost immaterial but managing the information inside of TSheets too is of course a bonus.