Ads for mobile apps are rarely personal; they're more often based on search keywords than your actual habits. Google is fixing this today with new ads in search and on YouTube that reflect your day-to-day app uses and purchases. If you regularly track your runs with fitness software, for instance, you may get ads offering to install a companion diet app.Google is also taking a cue from Facebook with keyword-based ads that launch into apps you have. Search for hotels on an upcoming trip and you may see an ad that takes you directly to an installed hotel booking app that would otherwise be gathering virtual dust. The smarter ads may ultimately exist to improve the bottom line for both Google and app developers, but they should also be a big help if you've had trouble finding the right app for your needs -- even if it's already sitting on your phone.