Best Taskman from SmartphoneWare, a über-utility, is now available for S60 3rd Edition (and also available for S60 2nd Edition and UIQ). Features include the ability to view information about currently running applications and processes, view information about installed applications and manage memory.

Best Taskman from Smartphoneware:

TaskMan helps you control your device better. It shows full information about device memory, running applications, processes, opened files and installed applications. The software allows extended applications management and much more functions to explore. 

It comes with views:

• Applications View - which shows which application is running and how much memory it is using. You can also close the application and find out more information about it.
  
• Memory View - which shows you memory information and allows you to 'free' memory.
• Process View - which shows you currently running processes.
• Installed View - which shows you which applications have been installed and where they are installed
• Open File View - which shows you currently open files.