Here's one dispenser that could solve the issue of storage space. Instead of separating olive oil and balsamic vinegar, the folks over at XD Design came up with a all in one bottle solution.

The Orbit features a pair of mouth blown glass globes that sit inside each other. They keep the two liquids separate.

The $30 Orbit includes a wooden base so it doesn't roll off the table and shatter on the floor after its first use. Very practical. [XD Design via Fancy]