You can check the url belo and can get an idea about the modules which are required in an admin panel
http://www.4guysfromrolla.com/articles/052307-1.aspx[
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PS: Admin panels are for managing the entire site whcih consist of following modules
1. Users
2. Contents
3. Permission of various pages.
4. Transactions (If website is performing any transaction)
5. Sending Newsletter ( If website has the provision for users to subscribe news letter).
So basically admin panels are for managing the website. So build/arrange your modules based on your actual website/webapplication.
Let me know if you require any other help.
:)