Ableton's Collections feature lets you label and organize any browser content so your most-used sounds, effects, and clips are always a click away. Right-clicking any item in the browser reveals the option to add it to a collection, and each collection has a dedicated number-key shortcut for even faster tagging on the fly.
Collections are fully customizable: rename them to match your workflow, remove items by right-clicking and deselecting the label, and use the edit button in the sidebar header to show or hide individual collections or library categories.