You can simply stack two or three pallets on top of each other. The wide square surface will be perfect for propping up your feet or setting a drink on.
Wood pallets are also a great source of inexpensive lumber if you want to design an outdoor coffee table from scratch that doesn't look like upcycled material.
For a casual boho or rustic look, leave the pallets in their natural wood tone and add a few coats of polyurethane to help keep the surface sealed against the weather.