This falls under the category of other applications that provide this functionality, but we’ve found that the Salesforce Labs Agile Accelerator works pretty great for internal tasks and work management. We’ve been able to Skuidify parts of it as well, and may eventually integrate it with our clients’ processes. 

Apart from that, seems like you could try a new custom object like Parent Task or Project that can have its own tasks, then use Skuid to make a really nice page for Parent Tasks/ Projects

Jack, thanks for the quick reply! Would it be complicated to create a custom object for Parent Task and then create a page for it? I am trying to create the Parent Task object now.

No it’s not complicated. When you create the object I think you need to check a specific box, something like Allow Activities, to make sure it’s an eligible Related To ID for the Tasks object. 

Then go to Skuid - Pages - Create New Page, choose a Page Template, then Choose Record Detail page and your new object name. 

Then, you’ll need to add a Model for Tasks, with a Condition that the Related To Id (WhatId) = field from another model, and choose your Parent Task object model. 

Thanks for helping out here Jack… 
Philip:  Welcome to rapid application development with Salesforce and Skuid.  Be careful - its addictive.