Foursquare - a hat tip
I have to hand it to the design team at Foursquare, they have really done some amazing work over the past year. In the time since I first started using the service until now they have been quietly, but rapidly adding layers of visual delight to every aspect of the UX.
From the main dot com site, to the mobile app, TShirts, infographics, icon designs and much more. Even the copywriting has subtly been getting better (see below).
Foursquare is clearly not a brand standing still. As well as rolling out to a selection of different langueages they are also engaging brands in the service. Offering special badges and discounts to followers of signed up brands. It's working well enough to get Facebook's attention.
I believe foursquare's design work is handled purely by an in-house team lead by Mari Sheibley. So my hat is tipped to you and your team.