Priority Pass have recently made two additions to their lounge network (outside of the normal additions they make).
Grain Store Cafe & Bar
This is located in the South Terminal after security. When you present your Priority Pass card you and accompanying eligible guests will receive £15 per person per visit off the final bill. Valid for any type of meal and/or drink. Full menu can be found here. Most non-mains items are under £15, with most mains in the £15-£18 range. So this is basically a free meal without a drink, or a starter with a drink.
Washington Dulles – Turkish Airlines Lounge
This is located in Concourse B, near Gate B43. This was added to their list of lounges awhile ago, but for whatever reason was not showing up on the priority pass website. This issue has now been fixed. Extremely nice lounge with showers, internet and pretty good food options.
I only mention these changes because they will likely be useful to some readers due to the sheer number of credit cards that offer priority pass membership.