Generally, when you have good domains you "don't need" to market them, as every now and then buyers contact you.

This guy has made good money:

http://www.businessinsider.com/micha...usiness-2012-4

http://news.cnet.com/8301-1023_3-574...s-in-24-hours/

There's other ways of packaging domains with social media depending on what the names are. I know a few business forums that go into some of this. Definitely not my forte though.....