I live in Terre Haute, Indiana. I have several "Summer Snowflake" viburnum bushes that do very well for me even in shade. This particular cultivar blooms all summer long and well into the fall, stopping only when hit by drought or a hard freeze. It isn't that picky about soil either as I have clay. The little flower clusters remind me of tiny hydrangea flowers. The bush also has pretty nice fall color although it isn't as vividly red as burning bush.
If you would prefer something in the rhododendron family, I remember reading about some hybrids that bloom as late as July and one variety that blooms in September. (These hybrids are supposedly hardy in zone 5--they are NOT the Encore azaleas of the Deep South.) If you're interested I can hunt up the information and nursery that offers them.