Steel tabletop fasteners are a great way to attach a tabletop to its base while still allowing for seasonal changes. On a table with straight aprons, it's easy enough to saw a kerf to hold the connectors with the tablesaw, but on a curved or molded apron that's not feasible. Instead, I've found that my biscuit joiner cuts these slots quickly and accurately.
My initial thought was "why not just use a router with a slot cutter?" Here's the simple answer. A biscuit joiner is always set up to cut slots. Using a router, you'd have to install the slot cutting bit. Not a huge time saver, but every little bit helps, right?