BMI is actually Broadcast Music International (like ASCAP or whatever).
The BMI/Lehman Engel Workshop was created by one of Broadway's greatest musical directors/personal champions, Lehman Engel, to nurture and promote the creation of new musical theatre.
It's a three-year class (the third year is in perpetuity once you get in). A lot of amazing talent have worked in or come from BMI, including Maury Yeston (who, for a good while, ran the advanced year), Flaherty and Ahrens...and, most recently, the poster boys for new BMI success, Robert Lopex and Jeff Marx.
Avenue Q was almost entirely created in BMI. I know many people who heard all those fun songs in their original incarnations.
I've worked on a load of new musicals coming in and out of that program.
The song I'm singing tomorrow (if you want to come stalk me) is from a musical called "Haunted." It's about the bizarrely supernatural circumstances around Abraham Lincoln (Rathbone, the general who was with him when he was assassinated, heard voices coming from his closet; Mary Todd Lincoln, who tried to communicate with their dead son)...my song is called "consequence" and is actually from an earlier incarnation of the show which focused more on Dr. Mudd, the man who set Booth's leg on the night of the assassination (the origin of the phrase, "your name is mud" is from this man, believe it or not). As the show has changed a lot, this character is much more minor than he was before but they're trying to find a place for this song as it's very interesting.
And now you know WAY too much, right?