When using a "Content: ID" contextual filter on a view you can provide a default argument such as "Content ID from URL". This module provides an additional option "Content ID of Alias Parent". This option will get the path alias of the current page ('/events/name-of-an-event' for example), then drops off the end portion of the url to get the "parent" alias ('/events' in our example) and returns the node id of that "parent" alias.

This assumes that your pathauto patterns are generating good URLs that follow normal patterns like the example above.