If you have a traditional bricks and mortar business, its a no-brainer that your business website would have a "Contact Us" page with the address, phone and fax numbers, location map etc etc.
But if your business is purely online and there is no physical address, how important do you think it is, from an SEO perspective, to provide a Contact Us feature, even if it is only an email address link? Would you think it's possible that missing contact info might be factored into the algos?
I'm looking at a parcel of 10 sites, with one going well and nine suffering. Just realized the good site is the only one with contact info and I'm wondering if that might have some relevance.... bit of a stretch I know but stranger things have happened!