There are 2 types of "pages" that SharePoint uses in Lists/Libraries:
- views - such as in AllItems.aspx
- Forms - DispForm.aspx & all.
The one you are referring most likely is the default view, such as in AllItems.aspx. One thing you could do is to enter that page in edit mode (append PageView=Shared&ToolPaneView=2) and add any other web parts (note that for lists using Lookup columns you could use in the ribbon the "Add Related Lists" which creates master-detail displays). Or use SharePoint Designer to access that lists folder (usually under Forms) and try editing (beware that removing web parts from the ones already available might induce strange behaviors, so rather hide that web-part) and add any XSLListViews by using Insert-DataView, etc.