Embrace might be my favorite of Ian MacKaye's bands. They strike a huge chord with me and find myself listening to their sole record more than any of the other Revolution Summer bands. The really crazy thing is that the band played roughly 9 shows in 9 months and that was the extent of their existence. Still, their lone album is a great record that never seems to get old. Sometimes, as much as I like Fugazi, I wish MacKaye and company could have kept this going for a few more years. "Said Gun", "Dance of Days", "Spoke", "Do Not Consider Yourself Free", "I Wish I", "Money", "No More Pain"...are all classics of punk rock and are usually sadly overlooked in comparison to Minor Threat and Fugazi (but still nowhere near as obscure as other MacKaye projects like Egg Hunt or Skewbald/Grand Union).
I would be completely remiss if there was no discussion of Rites of Spring at all when speaking of Revolution Summer; because in many respects, they were a major catalyst in its occurrence. I guess the best word to describe this band would have to be catharsis; any other explanation fails horribly. It is simple and complete. On record, I am sure there is much lost in the translation, but it is still there for those of us not there at the time.
Seriously, search out this book. Dance of Days: Two Decades of Punk in the Nation's Capital is an excellent document of several stages of DC punk and hardcore with lots of great anecdotal material.