Samhain has a new promo code, in honor of national LGBT Pride month: PRIDE30, gives 30% off on all their LGBT titles.
Don't know if it stacks with other discounts or not, but I do know we have enough M/M fans here that it's worth sharing.
ETA:
After combining the new discount code with my wish list (dangerous!) I can confirm Samhain still does not let you stack promo codes. However, codes still do stack with the "30% off new releases" discount.