APPA Mundi Tasks supports.
- Filter your Task list by Status
- Sort your Tasks by Status, Priority, Subject, Start Date or Due Date
- Create new Tasks on your Windows Phone
- Edit and Delete existing Tasks
- Synchronize with Microsoft Exchange Server 2007 and later
- Trial version supports a maximum of 4 Tasks
The designers knew they were plugging a hole is current Windows Phone 7 functionality, and therefore tried to make their app fit the design of the native Calendar and mail apps as much as possible, and appears to have succeeded well at this.
The app is $3.99, which is a steal for the business functionality it brings, and can be found in Marketplace here.