BMAH is designed to provide Black Market Auction House data to your fellow guild/raid/party members. Each time you visit the Black Market Auction House, BMAH will check to see if you have recently reported the items listed and the price. If not, BMAH will give you the option to announce the listings in guild, raid or party chat. BMAH will also check to see if there are any significant price jumps since the last time you announced.
Special thanks to jack445's Black Market Tracker (released under GPLv3) available here and Curse.com.