Zoho Tasks
The challenge when you start using multiple Zoho applications is that you start to create multiple Zoho Task lists. For example, you can have a task list in Zoho CRM, and then one for Support tickets in Zoho Desk and a task list relating to the projects you are working on in Zoho Projects. You need one unified view across all the Zoho apps and this is Zoho Tasks.
Zoho Tasks is a standalone application included within Zoho One. It also has a mobile version available.