It wasn't long after the shocking death of pop icon Whitney Houston was revealed to the world that tributes starting pouring in via Twitter. Whitney didn't have a ton of direct connections to the rock world, but that doesn't mean classic rockers don't have memories of and tributes to the singer to share with their fans. Below is a sampling of reactions from Slash, Heart -- check back later for updates, we'll put more posts up as more come in. R.I.P., Whitney.