Large versions installed with an angled nail can support up to 20 lbs. For heavier loads, use a flat-mounted hook and an anchor. Molly bolts These are not as easy to use as other drywall anchors, but they're still good to have on hand for medium to heavy loads. Pointed mollys can be tapped into place with a hammer. Once the molly is secure, unscrew the bolt and then replace it with the item in place.
Plastic versions are also available.
Metal toggle bolts can support heavy loads in drywall, plaster and hollow-core concrete block. Plastic versions hold medium loads in drywall and plaster. Fit the item to be anchored over the bolt, then insert the toggle and tighten. You can trim a plastic bolt flush with its nut after installation. Mechanical Plastics Corp. Dept.