Your pocket is finally of use: bundles just went live (see an example here). Using bundles, you can now aggregate your favorite picoids, create theme collections, and even put bundles in your bundles, so you can... well, you get the idea.
Notice that this is the first implementation of Bundles, and it's nowhere from being complete. There is no support for multi-selection, explicit cloning, or deletion. All these features will arrive somewhere in the future.
Next stop: animations.