First the easy one , Open Skype and then select Tools then Options. Now from the Options window go to the bottom and click Advanced then uncheck "Keep Skype in the taskbar while I'm signed in" then click saved.
Incredimail has something similar as Skype, Open Incredimail then click Tools then Options then Advanced, uncheck Aways display the Incredimail icon in my task bar. You may also need to right click the Incredimail icon in the the system tray and select Unpin too.
http://windows.microsoft.com/en-US/windows7/Change-how-icons-appear-in-the-notification-area