A new generation of mobile apps pinpoint a traveller's location and uncover worthwhile activities and attractions nearby, offering innovative functionality to rival Foursquare.

Last week, four free mobile apps debuted with a similar purpose: they all use a smartphone's geolocation software to plot a person's whereabouts on a map and reveal the most intriguing activities and attractions nearby.

While some travellers like to use a printed map and a list of attractions to chart their course, others prefer to be spontaneous from time to time. If you were, for instance, looking to take a break during a day of sightseeing, these impromptu-activity apps – Tripomatic, Triposo, Now and Schemer – can identify the most praised cafes, the most visited museums and the most buzzed about public events within a short distance from wherever you are standing. 

This new wave of impromptu-activity apps will have to compete against the gold standard of location-based services: Foursquare, which is a free smartphone app that tells friends where you're hanging out. Since its founding three years ago, more than 20 million people have used Foursquare to check in to millions of restaurants, stores and other venues, providing a giant set of data on the most popular places in destinations worldwide. This spring, Foursquare updated its app and website to include an Explore feature, which lists the food, nightlife, shopping and art venues near your location that have been praised by other Foursquare users. 

Foursquare has the most impressive database of opinions about local attractions and activities, but some new rival apps are hot on its tail, presenting similar information in even more clever ways.

is Google’s location-based activity recommendation app. Tell Schemer the neighbourhood you are in, and it'll suggest activities worth doing there. In mid-May, the company launched an iPhone app, after releasing its Android version in April. Schemer tailors its recommendations to the time and the weather, so if it's a rainy afternoon the app will recommend a museum visit instead of a long hike. To get more relevant suggestions, filter ideas by category, such as restaurants, outdoor, kid-friendly, beauty and cooking. If you're belong to the Google+ social network, the app will suggest activities similar to ones that are popular among your online friend circles. The app has global coverage.

Last week, Tripomatic launched an iPhone app that lets you shake your phone to see interesting places displayed on a map. (An Android version is in the works.) The unique advantage of Tripomatic's app is that it can sync up with a web-based itinerary-planning service, available for free at tripomatic.com, letting you pick the attractions you want to ahead of time and create a schedule for seeing them. Any spontaneous discoveries you make using the app can be added to the itinerary you've already created online, and the itinerary can also be accessed on the go. The app works with 400 destinations worldwide, with an emphasis on Europe.

Arriving on the scene last week, Now is an iPhone app that detects events taking place in four major cities (New York, Paris, London and San Francisco). In a clever move, the app discovers these hot events by analysing the amount of photos that are taken of the same event at the same location by others and that have been publicly uploaded to photo-sharing network Instagram. Of course, the app has its pros and its cons. On a recent sunny day in London, it pinpointed a spot in the city, Soho Square, where locals were eating lunch outside. A dozen people had uploaded photos of the scene, providing a good sense of what kind of crowd it was, and a map made the public space easy to find. But there was a time delay in reporting the event, so it appeared on Now at 2 pm, by which time many people had returned to their desks. Other activities listed within a 24-hour span included a flower show, a photography exhibition, a concert and a book signing by a famous author—some of which are events of long enough duration that you could track them down on a whim. Optional notifications can alert you when an event is happening in a city. There is no Android version.

Created as a website last year by former Google employees, Triposo (available for Apple and Android) suggests spontaneous day trip ideas based on where you are. In a unique touch, the app uses an algorithm to rank the most important attractions depending on factors such as how frequently cited they are online. The app also sorts attractions according to the time of day, favouring coffee shops in the morning and bars in the evening. In another nice touch, the app works offline after you've made an initial download of information for your specific locale, which cuts down on international roaming charges. The app works for hundreds of destinations but is strongest in major European cities.

Sean O'Neill is the tech travel columnist for BBC Travel