DSBM stands for Depressive Suicidal Black Metal and is a subgenre of Black Metal that deals with, well, suicide and depression. The songs tend to be quite long and have almost drone like qualities. Shoegaze I'm still iffy on. I pretty much just know it as almost dreamy Alternative Rock. Someone else could probably give you more background than I could. Then Black Metal/Shoegaze is the new found combination of Black Metal or DSBM with Shoegaze. The last page has a lot of examples of the Black Shoegaze stuff
DSBM
EDIT: Damn you Doctor!