Excel has a great feature that shows dependent and precedent cells for formulae. For those that do not know, here is a screenshot of trace precedents in action:

The blue arrow is indicating that Profit is dependent on Costs and Revenue. This is a great visual way to show how cells affect one another.
Whilst Anaplan has Drill Down, which is a great feature, I think another extremely useful feature would be Show Precedent Line Items.
How this would work:
- User right clicks on a line item and selects Show Precedent Line Items
- Anaplan will show the selected line item, and all line items (within the module only) that are precedent to the line item formula.
Using the excel example, if we had a module that had Revenue, Costs, and Profit line items; selecting Show Precedent Line Items on Profit would show Profit, Costs, and Revenue.
This would be incredibly helpful in larger modules where there are many line items. Additionally, where Drill Down limits your view typically to single list items, there's no reason why this could not be applied at a summary level.