Hi guys! Steve and I just say an SEOmoz Mozinar about citation building. Here are some notes:
They mentioned http://getlisted.org/ - seems neat at first glance.
Citations must be canonical. That is to say, they have to be as close to exactly the same format as possible everywhere they're made. Apparently the new Apple Maps is particularly sensitive to this.
Checking how USPS or Canada Post (or official postal service for the country) displays the address is a good guide for deciding which format to use.
Some have lists of LGBT friendly businesses - this is a good opportunity for citations (and link building of course).
Sites for immigrants like immigrant associations often have lists of local businesses that have staff/services for immigrants' native language. We'd have to find this out from clients, but it's a great opportunity for both citations and link building.
Flickr/Picasa/Youtube picture/video descriptions are a valid place for citations. If the client has accounts for these or could easily have them they're great places for citations.
There are a bunch of suggestions that, like with link building, the client would likely have to act upon... such as sponsoring or running local events, sponsoring kickstarter projects, giving testimonials to other businesses and asking that the full address be included, sponsoring local amateur sports teams and asking that they mention on the site...