When you want to unblock Files Types, First you need to do in SP Central Admin and then do in IIS for the specific Web Site. In IIS you won't see all File Types you seen in SP Central Admin.
SharePoint 2007
Go to Central Admin >> Operations >> Under Security Configuration you will see "Blocked File Types". Click on it and Select the required Web Application.
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SharePoint 2010
Go to Central Admin >> Applications Management >> Manage Web Applications. Select one Web Application and you will see "Blocked File Types" listed.
Open the IIS Manager, go to Sites and Select the required Site. Under IIS, you will see the option "Request Filtering". Open (double click) it.
SharePoint 2007
Go to Central Admin >> Operations >> Under Security Configuration you will see "Blocked File Types". Click on it and Select the required Web Application.
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SharePoint 2010
Go to Central Admin >> Applications Management >> Manage Web Applications. Select one Web Application and you will see "Blocked File Types" listed.
You need to remove the required Files Types from the "Blocked File Types", to allow them.
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IIS
Open the IIS Manager, go to Sites and Select the required Site. Under IIS, you will see the option "Request Filtering". Open (double click) it.
You will see all Blocked File Types with Allowed 'False'. Make it 'True'.