There are a couple of nice postings on the topic of the possible values for the attributes GroupId and Location in the Feature element manifest file. Chris O'Brien has a good listing of possible values and Robin Meuré recently extended on it by pointing to a specific SharePoint control (the FeatureMenuTemplate control) responsible for the inclusion of the dynamic hyperlinks or other custom actions made available through Features. Actually, this is not the only control that is capable of doing this. You can find similar controls in many places. For example, when you want to add a hyperlink to the Site Settings page, you can navigate to the C:\Program Files\Common Files\Microsoft Shared\web server extensions\12\TEMPLATE\LAYOUTS\settings.aspx. Open it in Visual Studio and you'll find at the bottom of the ASPX the following definition:
CellPadding="1" CellSpacing="2" Width="100%"
Isn't SharePoint fun J...