what SharePoint version are you using? if using SharePoint 2010, you could use enterprise search or Fast and configure the refinement panel.
Another solution might be the content by query webpart in combination with the technique you mentioned (calculated fields), but I am not sure if you can work with 50+ lists, it totally depends on how you designed the the lists (all based on the same content type, same list definitions, etc.?!)
edit: I assumed you wanted to aggregate 50 lists and create a filter on that. After reading your post again, I see that you have 50 separate lists, which all need the same view.
I can imagine that you could copy the views using sharepoint designer 50 times. Another possibility is to configure the content by query webpart one time, reuse that one and reconfigure it 50 times for the 50 different lists. That way, you don't have to use visual studio at all.