Microsoft's suggestion for how to pass those hot summer afternoons: spend 1200 Microsoft Points ($15), repeatedly. The company released the official dates and prices for the XBLA games in this year's Summer of Arcade promotion -- or, rather, dates and price, since they all share the aforementioned 1200 MSP price tag.
Like last year's Summer of Arcade, purchasing all five games in this year's lineup entitles the buyer to a 1200-point rebate (essentially buy four, get one free). Additionally, if you buy three of the five, you'll get 400 MSP back! As for the release schedule:
Limbo: July 21
Hydro Thunder Hurricane: July 28
Castlevania: Harmony of Despair: August 4
Monday Night Combat: August 11
Lara Croft and the Guardian of Light: August 18