According to comScore, in 2010 nearly half of all US mobile subscribers described themselves as mobile media users, having browsed the mobile web, used apps or downloaded content — up 17 percent from 2009. With regard to mobile commerce, results from a recent study conducted by ForeSee show that a third accessed a retailer’s website from their phones in 2010, up from 24 percent in 2009. And in fact, mobile is projected to overtake PCs in 2011 according to a Deloitte whitepaper, with a storm of tablet devices helping fuel the opportunity and obsession. With excitement high, brands and marketers are diving in to experiment and take advantage of this growing mobile marketing opportunity. Here in Boston we have several mobile marketing technology companies, and below are three that corner different aspects of the opportunity:

Celtra

Cambridge-based Celtra makes running mobile ad campaigns across different networks and devices a cinch. The company provides a self-service platform for publishers, ad networks and media agencies to create, distribute and measure mobile display ads. Their solution spans all major mobile operating systems and across devices, and even offers analytics tracking.

With Celtra’s AdCreator, you can easily build a mobile ad with depth that looks an acts like an actual app. You can include and re-order any number of interconnected pages, including repeatable menus, backgrounds, animations, and even component additions like games, forms, and 360 degree views. When you’re ready to publish your ad, Celtra pushes it to various mobile ad networks (of course including those based right here in Boston: JumpTap, Nexage, and WHERE). As your campaign runs, Celtra then offers analytics: impressions, clicks, and what pages and components people are clicking on and interacting with most. You can then optimize your ads and tweak them as you learn more about what works and doesn’t work – yes, even while the campaign is still running.

Celtra launched its initial platform in April 2010, and is currently operating out of the Cambridge Innovation Center. In January the company announced a $5M Series A round led by GrandBanks Capital and Fairhaven Capital. Celtra boasts an impressive client list already, including Starwood Preferred Guest, NBA/Champs Sports, Evian, Marriott, Jones New York, Volvo and Kmart. Check out examples of mobile ads leveraging Celtra here.

Nellymoser

Arlington-based Nellymoser has a mobile engagement platform that makes it easy to turn printed action codes — from SMS short codes to QR codes — into instant, interactive, active engagement. When a consumer follows instructions to capture that code using their phone (“snap,” “click,” text”), Nellymoser delivers an interactive engagement experience ranging from contests and video to an actual e-commerce gateway for payment.

Nellymoser’s platform supports a variety of digital media input for marketers, from multimedia like live HD video, images and music to advertising feeds and even APIs. Marketers can select from a variety of mobile engagement types like rich micro-sites, sweepstakes, subscription opt-ins, social media, apps, and even mobile commerce. Nellymoser delivers that content across networks thanks to a device-side client that is compatible with hundreds of millions of handsets. The company boasts that, “Whether you have HD video, live audio streams or a thousand high res photographs, Nellymoser’s platform tools allow you to quickly and reliably ingest your content so that it can be successfully delivered to the myriad of mobile devices on the market today.”

Nellymoser was founded in 2000 as a technology company focused on audio and video for networked consumer products (Xbox, Playstation, Leapster). Their technology to date can be found in over 1B networked consumer products. The company’s foray into mobile began in 2002, when it focused on building a solution to deliver rich media to the mobile sector. Examples of some of their campaigns and clients to date include a mobile experience for the 2011 Sports Illustrated Swimsuit Issue, mobile video fro Jessica Simpson, sweepstakes with Martha Stewart, social media with Timberland, and a video playlist with Lucky Magazine.

KangoGift

KangoGift is bringing the convenience of gift cards and fun of virtual gifting that swept Facebook from the onset mobile. As a consumer you can sign up and send virtual gift vouchers for things like flowers, cupcakes or movie tickets over text-message to friends and family. The recipient will receive a voucher code (with a more visual voucher for smartphone owners), and all s/he needs to do is show that code to the cashier for redemption.

KangoGift’s product selection is a result of the merchants and businesses the company has partnered with, most of which are currently right here in the Boston area: small businesses and large like Wired Puppy, Fandango, Tis Tik, Cambridge Artists Collaborative, The Melting Pot, and Berry Line. In 2010 the company worked closely with 60 partners in the area to refine its technology and believes 2011 will be a breakout year thanks to the primed and ready mobile commerce sector. With the tagline “instant gifts by cell phone,” KangoGift works across smartphone and feature phones alike.

KangoGift was founded in 2009 and this January Bill Warner made an angel investment in the company. KangoGift was one of 10 mobile tech companies featured last year in Entrepreneur Magazine’s annual 100 Brilliant Ideas feature.

What other companies did we miss? Let us know in the comments!