OSHA changed the rules for residential construction workers on March 15th, 2013. No longer will they be issuing reduced fines, helpful hints, and consultations on compliance with the fall protection regulations. They are in full-enforcement mode, and you should be in full-compliance mode if you want to avoid serious penalties.
Unless you are able to plausibly demonstrate why conventional fall protection is not feasible or why it presents an even greater hazard when used, your residential roofing or construction company will be cited by visiting OSHA enforcement officers if workers are not protected by active fall arrest systems, guardrails, and/or safety nets, depending on the site situation.
Any work conducted 6 ft. or move above a lower level must be protected. For construction workers and roofers, this may seem like a laughably low threshold. But OSHA has thousands of cases of research on it's side. Their goal is workers safety and creating environments where necessary work can be completed in as safe a manner as possible.
For residential building and roofing, there are three main focus: Anchorage, Body Support, and Connectors. For the most basic and least expensive compliance, there are kits like Protecta's Compliance in a Can. This simple but effective roofer's fall protection kit features a DBI-SALA reusable roof anchor, 50 ft. of stout, dependable rope lifeline, a rope grab, and a full-body Protecta harness. The rope grab moves along the lifeline and grabs hold in the event of a fall. Special stitching will release under a load to reduce fall forces.
The next step up the protection ladder is the Deluxe Roofer's Kit from DBI-SALA. This kit features similar equipment the the Compliance in a Can, but it's all generally more robust and comfortable. For instance, the Delta No-Tangle harness has a stand-up dorsal D-ring, and quick-connect buckles. The rope grab has a longer line attached for greater mobility, and the lifeline comes with a counterweight to keep it hanging in the right direction.
For greater rooftop or construction zone coverage, horizontal lifelines are available for either one or two workers. These systems have the benefit of allowing a wide range of movement over the work area. Two workers can work together while being safely connected to a central fall protection system. The Sayfline 2-Person Horizontal Roof Lifeline Safety Kit comes with two sturdy roof anchors and a horizontal line between them that both workers attach to.
All of these systems need to be deployed with care. Fall protection that doesn't actually stop a falling worker before they impact with the next level or the ground is not helpful. Fall clearance distances need to be carefully considered.