I have several clients who have stocks that trade. These are penny stocks. Generally under $1.00. They are looking for new ways to get the word out about their company but no spam emails. Seem open to all ideas.
Start a thread on TheLion.com or other similar stock forum about the company. That usually gets people talking about it. Maybe also consider an advertising slot on something like bigcharts.com
Post their announcements on special sites. If they have activity they should make press releases... In fact the best way is to have a profitable activity. This is the best way to increase the value of their company and consequently of their shares. I know because I am involved in such a company and this is what they do... Egomancer
you have to be very careful legally with regard to stock pumping and insider trading. let the company stand on its figures and business strategy, that will take care of the share price, not advertising the stock.