We're still able to post in the library, the rec center, lots of locally owned businesses (especially restaurants) etc. Of course, as you say, most of the corporate stores where everyone actually is don't usually allow it.  As far as publicizing auditions the best bet is to compile an email list of actors and potential actors. 

Our theater moved away from psters a while back.  I found that we just weren't getting enough bang for our buck.  Either we were not able to put our poster up, or the poster was getting lost amongst all of the other public bulletins.  Our posters were ending up as souvenirs for cast and crew.We rely on emailing our list, website, Facebook, and press releases to every newspaper in the area.  It's free, and have been getting pretty good results.

We also print 1/2 page fliers or have vista print business cards printed (color, show logo, dates, times, prices, and box office contact info) and hand those out to the community.  We give them out to all the actors to hand out or put in their place of business.  In addition, we have actors dress in appropriate costumes (although not necessarily the one's they actually use in the show - too risky!) and wander the farmers market or the like, handing out cards or flyers.  We have found this to be very successful in getting the word out about our shows.  We do still use posters, but in my opinion, they are not a very successful marketing tool.  Community reader boards (manual post and electronic) are great - and the banks in our community are happy to post non-profit event info on theirs.

I'm curious, how many of you ask the actors in the show to post on facebook, social media about the show?

I think we are at a curious juncture in promoting shows.  First, the old media is decreasing in value (posters, newspapers, radio).  Second, the electronic media (websites) are very impersonal.....and every body says 'personal' is the way to promote....so that leaves word of mouth and social media.  I don't think anybody in community theatre really effectively uses social media (surprise me!)... they may have a social media page, but that's about as personal as a website.

So how many ask their cast and crew to post on facebook and social media about a play that they are in?  How many ask their cast & crew to 'like' a theatre company's facebook page?

Is there something else that you all do?  I'd like to start a discussion on how to effectively use the current tools.

We create an event page on Facebook and then ask everyone involved to "invite" all their facebook friends. That has wound up being anywhere from 500 to 1500 people who all got a personal invitation from someone or some organization involved.  It's probably loosing effectiveness as FB is flooded with promotional material but it can't hurt.  My belief is that it's at least if not more effective than posters at this point.