Here's a quick one -
When performing Bulk Merge, you may want to actually see the merge result on the Customer record (same as how you can see emails sent to the Customer on his Message tab). But you may have noticed you don't see Bulk Merge activity on the Message tab.
Well, the answer is that you must customize the Customer's form, and, on the List tab, tick in Bulk Merge. You'll see all Bulk Merge activity on this tab.