I have a personal and business profile on facebook. I keep all personal stuff out of the business profile but do regularly share business info on my personal profile.
Twitter is more free form for me. I do what I want in Twitter, link to loads of interesting stuff and to all my other social stuff and the odd one back to the business as well.
Being viewed as a spammer is all to easy in these environments a good rule of thumb is link to 9 other sites for each link to your own.
Be part of the community not a broadcaster.