Switcher a freewar task switcher is now avialable in version 1.4. It is also available for the Series 60. The program is invaluable in helping out with memory issues.

Task-Switcher will let you:

list your running applications
tell you how big they are in terms of memory usage
close applications
switch to an application even if it is not a graphical one

In short: You regain the "Open Programs" utility, which you originally lost in EPOC R6.

http://www.ki-ag.de/html/tech/nokiaswitcher.html