Classified ads have come a long way from the old newspaper listings, becoming their own entity dominated by giants like Craigslist and eBay. Unfortunately for those Goliaths, San Diego-based Barefoot Solutions has unveiled its mobile market David equivalent: Antengo.

If the only question that needed to be answered in regards to Antengo's aim of providing real-time classifieds was, "Does the app work?" -- the answer would be a resounding yes. Antengo's entire interface is streamlined, simple to use, and downright slick. You can jump right into browsing postings from the moment the app is downloaded, and even though you have to sign up to create a listing, you can do so with your Facebook or Twitter account to minimize the amount of info you'll have to enter.

Once you're navigating listings, you can switch between list, map, and photo view to see what is available in your area. Posts you create go up almost immediately, and ads are updated quickly if information is changed or added. The real-time emphasis could be great for day-of purchases and quick buys.

The key phrase in the previous sentence is "could be great." The biggest problem Antengo faces -- and the reason that its potential hasn't been reached -- is building a user base. It's going to be an uphill battle to pull people away from established services to a new one, and until that happens, listings outside of major cities and heavily-populated areas will be (and currently are) sparse.

The bottom line. Antengo sports an excellent interface with some fantastic features that improve upon the basic concepts laid out by classifieds apps before it, but it may have difficulty convincing people to ditch their current classifieds of choice. And until (or unless) that happens, it's not quite an essential destination for buying and selling goods.