1. A method for indexing resources for an application on a client device, comprising: identifying a first resource package and a second resource package on a client device, the first resource package comprising first supplemental data used to provide first optional user experience functionality for an application, the second resource package comprising second supplemental data used to provide second optional user experience functionality for the application; merging a first resource index for the first resource package with a second resource index for the second resource package to create a merged resource index, the first resource index describing first resource data and first resource applicability data for the first resource package, the second resource index describing second resource data and second resource applicability data for the second resource package; and utilizing the merged resource index to selectively utilize one or more resources for execution of the application.