Tempting though it may be to give you the standard list (Rocky Horror Picture Show, anybody?) I shall resist. As I'm not quite sure what you're looking for, the few that come to mind are C.H.U.D., Troll 2, Hard Ticket to Hawaii, Cannibal Holocaust, and Grindhouse. These fall into the 'so bad they're good' category.
If you're looking for something a bit more high-brow, you might check out Captain Kidd, East of Borneo, Night and Fog, Utopia, The Brother from Another Planet, and Kiss Me Deadly. These are considered classics, even cult classics, by the not-so-much-B-Movie-as-obscure-movie club.