The Prompt With List action (v8+) lets you select from a list of values. The values should be placed on separate lines, and can come from a clipboard, variable, file or text within the action.
You can include a title (which is only displayed when the search field is empty), as well as a default search string (v8.1+). You can also configure the width of the window (narrow, normal, wide, automatic) and whether to allow multiple selections (v8.1+).
If a single entry is returned, it is returned by itself (no newline character). If multiple entries are returned, they will be returned as multiple lines, each followed by a newline character (8.1+).
The values are displayed in a Spotlight-like window, similar to the Trigger Macro by Name action.
The selected item will be saved back to the source of the list, or to a specified clipboard, variable or file.