Yelp has been on a roll, and is now reporting that it gets 29 million unique visitors a month. Given that, the company’s immediate challenge is to move beyond its core base of restaurant and shopping reviews and dive deep for Yellow Pages-arena services reviews, as well as reviews for classified categories, such as autos and real estate/apartments.

Restaurants currently make up 29 percent of reviews, while shopping constitutes 23 percent. Other major categories include beauty and fitness (9 percent), arts & entertainment (8 percent), home and local services (7 percent), entertainment (5 percent), and nightlife (4 percent).

Apartments are certainly a good place for Yelp to concentrate on, especially given the youthful target sought by apartment managers. Almost half of Yelp’s users (46 percent) are between 18 and 34 years old, while 36 percent are between 35 and 49.

So it was no surprise that Yelp COO Geoff Donaker was out evangelizing the cause this morning on a webinar conducted by NCI’s Apartment Finder, a leading publication for managers of mega-apartment complexes.

The evangelism effort’s a good idea. In a survey before the call, just 35 percent of the webinar audience said they were already familiar with Yelp, and just 5 percent said they were already engaged with Yelp as a business owner. Sixty-one percent, however, said they had never heard of it.

Donaker told the webinar attendees that while he hoped they eventually advertised on Yelp, he was mostly interested in getting them tuned into Yelp as a marketing resource and to get them to access their business owner accounts and improve their pages. He noted that most reviews on Yelp were actually positive ones and they shouldn’t be afraid of the community feedback.

Many apartment managers, however, have cold feet vis-a-vis reviews due to what Apartment Finder VP of Operations Judy Bellack suggested was “extremely negative” experience with one site in particular: Internet Brands’ ApartmentRatings.com.