I had a verbal agreement with a contractor to complete work for $30K by April 2008 (work started Jan 2008). He did not meet deadline and never finished final details of project. Said he was "done" end of September 08. He used an additional $10K of my Home Depot credit line to purchase supplies and I paid over $6K for cabinetry/ kitchen remodel (totaling over $46K). He JUST (Feb '09) sent me a bill for over $11K and is threatening a mechanic's lien for twice that on this and another one of my properties. He has nothing in writing. I have proof of payments, proof of payments to another contractor to complete and correct his work, proof of correspondence with a real estate agent on work expectations that were not met (impacting his ability to market the property).

Can he file a lien? Do I need to get an atty?

Your problem here is that its pretty easy to file a mechanic's lien. So you might not be able to stop it. However, if one is filed, you can sue him to have it removed.

In the future you should do nothing if its not in writing.