For the purposes of this article, consider that a badge is an artifact of recognition. There are other connotations for the word "badge" involving authority and power—but let's ignore those for now.
Badges are collectable, and that collection can made visible to other people. A badge collection tells the story of things that other people have declared about the person who owns the collection. A badge collection is also a set of things that the owner has chosen to share.
This puts both the badge presenters and bearers in control of assertions—which means badges have something to say about all parties involved: The set of available badges is a comment on things valued by the community that presents them. Conversely, badges accepted and displayed by a person can help demonstrate what values he or she shares with the community.
And beyond what they assert, badges are social objects. People have opinions about badges, the people who present them, and the people who claim them. Some applaud the sentiment behind particular badges; some congratulate the people who claim them; some people make plans to earn them. Some badges are more attractive than others, some are funny, and some are more difficult to achieve. This is all context that make badges interesting beyond just what they assert.
Imagine that someone does something at an event that you really like—say it's a science fair demo or a lightning talk. You could pull out your smartphone and nominate them for a badge on the spot.
Or, say a speaker at a breakout session wants to engage the audience by handing out badges. The speaker could offer a code that represents a ready-made nomination for you, as the reverse of the previous scenario. This is kind of like the location-based "check-in" offered by Foursquare and others, only tied to a more abstract event or happening.
As social objects, badges on the web are identified by URLs and can bookmarked and shared. People and badges can also be given shorter identifiers that are friendlier for typing on mobile devices.
If you don't have someone's profile in Badger bookmarked, a glance at their name tag could give you a short user name or code to tap into a nomination form. Maybe it could even be a QR code on their event badge that you snap a picture of to submit the badge nomination.