Fondu is a new iPhone application, dubbed the "Foursquare for Foodies," that has promise, in that it marries the geo-location aspect of Foursquare with the review capabilities of a site like Yelp. In other words, you can actually get a quick snapshot thought of a given restaurant or bar from someone you know.
Fondu, from the creator of SpotOn (which married your social-media likes and online friends to recommend everything from restaurants to shopping choices) lets you search for restaurants nearby or pull up places you've checked in with on Foursquare. You can then rate (one to four petals) a given place and write a short review. If you want to find out what someone else thinks of a given place, your friends' reviews are in a feed based on where they've been. You can also search a map for popular restaurants nearby.
This is a big step for two reasons. First, you're more likely to value what a friend thinks of a restaurant rather than a guest reviewer on a given website (much in the same way that you would trust a more highly rated reviewer with a long history of posts on Yelp). It takes away some of the capriciousness with online accounts of an evening out. You know if your friend is easily impressed or irritated and can judge what you think your own experience would be accordingly.
Second, it gives you access to a real-time advice guide for where to go, which is one of the only times I use online review sites or restaurant map listings (when I'm in an area I don't know that well and am looking for some quick guidance that will steer me clear of a chain restaurant).
Fondu is an interesting concept in that it moves the online experience closer to what is the standard for an offline experience — telling a friend about a great new place you tried.