Here are some real world examples of REST web services
1. Twitter APIThe Twitter micro-blogging service includes two RESTful APIs.
The Twitter REST API methods allow developers to access core Twitter data like timelines, status data, and user information.
Sample Resource description
GET statuses/retweets/:id Returns a collection of the 100 most recent retweets of the tweet specified by the id parameter.
GET search/tweets Returns a collection of relevant Tweets matching a specified query
GET followers/ids Returns a cursored collection of user IDs for every user following the specified user.
GET users/suggestions Access to Twitter's suggested user list.
2. Last FM APIThe Last.fm API allows anyone to build their own programs using Last.fm data, whether they're on the web, the desktop or mobile devices.The RESTful API allows for access to the last.fm music data resources - albums, artists, playlists etc.
Last FM REST API
Last FM API Intro
3. LinkedIn APILinkedIn is the worlds largest business social networking hub.
The REST API provides a simple, consistent representation of people, companies, jobs, and the interactions and relationships between them.
LinkedIn REST API Documentation