Mark all above as read?

Is there a way to mark all items as read above or below a point in the list view? Something like “Mark all above as read”. Google Reader used to have something similar. The use case for this is for feeds that I like to skim the titles of, but I don’t always get through the entire list in one view, so I’d like an easy way to mark what I’ve already skimmed so I don’t have to go through it again (but not touch the items that I haven’t skimmed yet).