If you wanna make loot or objective markers, then maybe the crates from the battlefield accessories might be a good place to start? Mount them on large round bases, scatter a few shotguns, lasguns and pistols, maybe have some sticking out from under the lid of the box and that should give you some nice looking markers.
A bit big, but at least you'll be able to see 'em!
On the aside, have you seen the new Chaos Cultist models? They just scream Necromunda to me!