Yes, Angies List and the Better Business Bureau. Pick up specific local code variances (from National Code) from the building department. Try to talk with some of the building inspectors and ask for their advice. See if they have a file of complaints from homeowners about contractors. See if they have an approved list or recommendations. In La Grange Park when I looked at the complaint file, more than half of the complaints were about Father and Sons. But if you ask the inspector, he can't say, "Don't use Father and Sons." In Oak Park, they won't give you recommendations but when I asked if Georges Concrete was on their approved list, the response was, "Yes. (sidebar) He is great!" They might say something like, "Yes, Budget Right Kitchens is registered to do work in Oak Park but we have received a complaint."
Two plumbing companies I would recommend include: Aleck Plumbing 708-799-4670 and Morning, Noon & Night Plumbing: 773-880-0072. Heat & Air I would recommend Assured Air 708-839-5760.