At last count there were over 100,000 apps available for the iPhone. By any measure, that’s an amazing number! Like any collection of goods, the available apps range from outstanding to outlandish, but if you’re anything like me you’ve found at least a few apps that have impacted your life in big ways.

Yep, apps are big business, which makes it all the more surprising that more marketers aren’t actively optimizing their apps through the use of software like Omniture’s Test&Target. You heard me right: You can use Test&Target to optimize iPhone apps with all the great functionality you’ve come to expect, like A/B and multivariate testing, dynamic content targeting, and user segmentation. Omniture Digital offers in-application optimization services for our customers, and it’s exciting to see this new service take off. Here are some of the biggest areas of opportunities that our clients are looking to improve:

Registration and lead generation: Many apps offer an option to register for enhanced services, and I’ve seen these processes run the gamut of superb to awful. Just as on the web, the way you present a registration process can make a huge impact on your conversion rate. Areas to focus on are the number of fields required, the order in which you ask questions, and even the offer you’re presenting to your customers. Test&Target can serve two or more registration flows to your users to measure which one performs better.

In-application e-commerce: Some of the biggest gains Omniture Digital has made for our customers comes from making improvements to a standard web checkout process. An in-app checkout process is even more critical, as you have only a few seconds before a user will abandon if the process is not super simple. Test&Target allows you to refine and measure your e-commerce flow, without having to release a new version of the application.

Content targeting: For content applications (such as news or blog apps), content targeting can be a powerful tool for keeping your users inside your app longer and coming back more often. Test&Target can target content based on preferences stated by your app’s users, or simply by keeping track of past interests. And don’t forget the power of geo-targeting.

In-app upsells: Now that Apple has OK’d in-app purchases and instant app upgrades, it’s time to pay attention to how you’re messaging these options to your users. Why pass up a chance to test out an improved offer or call to action? A dynamic A/B or multivariate test can do the trick here.

Product recommendations: For e-commerce applications, product recommendations can be a huge driver of app usage and sales. If your app ties into your product catalog (and even better, into your SiteCatalyst data), then you are in a position to help your customers discover more products in the few seconds that they’ll be spending with you.

I’m really just scratching the surface here. I’m looking forward to the day when I can pick up an iPhone application and know that the entire experience from start to finish has been optimized by the votes of a million thumbs just like mine.