It seems like the Baltimore folks have this, so why shouldn't the DC hounds. This is a place to post specials that particular restaurants have.
Here's what I know about:
*Ardeo- Thursday Night Wine Dinner
$52/person gets you a 4 course menu paired with 3 two ounce glasses of wine
*Butterfield 9- $38/person 3-courese dinner menu pre and post theater. Pre-theater is Daily 5:30-7pm and post-theater is Sunday-Thursday 9pm-10pm. And Friday and Saturday 10pm-11pm.
*David Gregory- Happy Hour Monday-Friday from 4:30-7:30 (and until 10pm on Tuesdays). They have $5 appetizers and drink specials
*Merkado- Pre-theater dinner= $25/person. Served daily from 5pm-7pm. You get a choice of small plate, big plate, sweet plate or a glass of wine. They also have really good Happy Hour drink specials daily 4-7pm
And probably the best kept secret in DC:
*Tabernade Alabardero- 1/2 price tapas and cheap Sangria Monday-Thursday until 7pm.