I do real estate closings on the side...I have represented both parties at closings, with the consent of both parties.
As far as selling by owner goes, I have also been involved in these transactions. There are things you have to be aware of. i.e. you won't get as many people looking at your house, unless you get it listed on the MLS, (but if you do get it on the MLS, agents will be bringing clients to you and will be expecting commissions). Make sure that if you sell by owner, you get/use a Standard Real Estate Contract (places like REMAX will sometimes sell and/or give them to you), don't deviate from it, and make sure you get it to your attorney within the Five (5) day attorney approval period.