A new mobile-phone service promises to make shopping easier by locating stores that carry the product the user craves. Other kinds of cell-phone software help people find the nearest store of a certain type–electronics, shoe, or hardware, for example. But the new service, called Slifter, claims to be the first to find specific products within stores.

It’s a great idea–in theory. In reality, Slifter generally provides long product-information lists that aren’t always useful and don’t have data from every retailer. Still, this indicates where location-aware mobile technology might be headed if the underlying data were more comprehensive and mined by better search engines.

To determine a starting point for each search, Slifter uses GPS hardware embedded into cell phones; alternatively, a user can enter his or her zip code. But a Slifter search made near Boston for the words “ice cream” sent me to a KB Toys store for a toy with “ice cream” in its name–no actual ice-cream retailers appeared in the results. Equally frustrating, a search for specific car models only gave me online car listings. In fairness, the New York City startup says it’s not trying to master cars or food. And its CEO, Alex Muller, says the company is “backfilling” search requests with online listings, reckoning that consumers would rather find something than nothing.

Muller says that Slifter’s forte is consumer electronics. That may be true, but the first hit on a search for “iPod Nano,” performed in Cambridge, MA, suggested that I buy iSkins–an iPod accessory–and that I should do so at a CompUSA store 26 miles away, in Salem, NH. I had to scroll through five screens of search results to find an actual iPod Nano music player. Even then, the software did not suggest the Apple retailer a half-mile away; instead, it sent me to an electronics store farther away. Similarly, a search for a Motorola Razr phone gave tons of listings for accessories. After I scrolled down to the first actual phone listing, the software suggested, oddly, the CompUSA outlet in faraway Salem, NH, again.

When I asked the company to suggest a search that would best demonstrate Slifter’s value, I was told to search for a Canon D40. Sure enough, the first listing accurately showed many nearby stores selling this common model, complete with distances from my location. While any yellow-pages search could have given me the same list of big-box electronics stores, there was indeed a glimmer of hope. I could see from my Slifter search that all of the stores were selling the Canon D40 for the same price: $599. This search return could, in theory, spare me from wasting time hunting for discounts.

Slifter currently has 200,000 members, most of them using the free application (which allows searches only by zip code); a $1.99 monthly subscription allows the more-precise GPS-based searches. Companies also pay Slifter a small fee each time a user opens a search result.

Paul Rademacher, a software engineer whose credits include superimposing Craigslist real-estate listings on Google Maps, says that Slifter’s interface needs work. “The problem is that the results are not organized … and there’s almost no information provided with the link.”

Muller argues that Slifter could get better if more retailers furnished information. “Here’s the way we view it,” he says. “In 2007, most retailers, irrespective of size, are managing inventory electronically with programs like Quicken Point of Sale. These can let you export your inventory.” Slifter updates its database daily.

Jeremy Kreitler, director of product management for Yahoo Maps, says the big players in search aren’t yet attempting Slifter-like services because of the lack of “great, comprehensive, clean data” on inventories. Outside of consumer electronics, inventory data often isn’t available, or the quality is “questionable” at best, Kreitler says. That’s the main stumbling block; creating better search tools is relatively easy, he notes.