Re: Open house?
Definitely have a website and get it listed in the AikiWeb and Aikido Journal dojo directories. If you go Google "aikido information" AikiWeb is the 2nd entry and the rest of the top entries will link you to AikiWeb and/or Aikido Journal.
Along with the website our best advertising is word of mouth. Get your people talking about the dojo and what the training is like. We have had open houses and done demonstrations but they rarely bring any significant number of students. We still do them because they're fun and we feel we should still make our presence known but we've stopped expecting or hoping for an increase of students from them.
You could also contact the local newspaper and get in touch with their "lifestyles", "local happenings" (or whatever they call it) editor and see if they'd be interested in doing a story on you, especially if you have some type of anniversary or other milestone coming up. If you have a local TV station you can contact them also. It's a good (free) way to get your presence known to a large portion of the community.