With so many people using smartphones, everyone is searching for ways to reach would-be customers on mobile apps and websites. Here are three mobile-advertising services tailored for different business needs.

This service, which reaches about 4.5 million people in the U.S. through ads on a network of mobile apps and websites, is designed to drive foot traffic to storefronts. After setting up an account, log on at yourchalkboard.com, enter your business's location, and submit a 160-character promotion. If someone in Chalkboard's audience comes within a mile of your business, the ad will appear in an app or site on the person's phone. Cost: $360 for one year of unlimited promotions

Moolah Media
Tailored for direct-response advertisers, Moolah lets you deliver ads via text messages, apps, and mobile browsers. Working with an account rep, you can target demographics, cellular networks, and devices, paying only when a prospect calls your company or fills out an online form in response to an ad. Moolah's site provides real-time reporting on impressions, clicks, calls, and form submissions. Cost: $2 to $3 per lead, on average

This keyword-based DIY service, which reaches an audience of 85 million people worldwide, lets you create text-message promotions and banner-ad campaigns for mobile apps and sites. On the site, you input texts and upload banners, set daily budgets, bid on keywords, and target carriers, demographics, devices, and locations. Cost: Starts at 5 cents to 10 cents per click for a basic campaign