The south Indian state of Tamil Nadu has been declared a "disaster zone" as heavy flooding killed at least 280 people. The Indian army was deployed to rescue thousands of people who were stranded after the region received the heaviest rainfall in a century.

While rainfall has ceased for the moment, thousands still remain trapped or displaced due to the heavy flooding. While many have begun taking to social media to offer their prayers and support for the victims, a number of businesses and companies have stepped forward to help the flood victims in whatever ways their services are able to.

IBTimes UK has rounded up 10 of the best initiatives set up by businesses to provide aid to those affected by the flooding crisis.

1. Uber

Using Uber's uberCARE service for Chennai, people were able to request the taxi service to pick them up free of charge. Uber replaced their traditional taxis with trucks, which they said were better able to deal with the waterlogged streets.

Apart from offering free rides in the region, people could also request a truck to come to their doorstep and collect essential supplies to donate to the flood victims. Uber would then deliver the supplies to the necessary locations, however, people were also able to specify a location to which they wished the supplies to be dropped off at.

2. Twitter

As many Indians began taking to Twitter to coordinate relief efforts in the region, Twitter India's account became a central rallying point for the different ways people could assist during the floods. Twitter India has been rounding up all the different volunteering services that are taking place for the flood victims, as well as organising the different hashtags related to the floods by ensuring that people are using the correct hashtags for the correct purposes. The account was also providing useful emergency contact numbers and updates on the situation on the ground.

3. Facebook

Facebook activated their "safety" tool during the floods to help people let their loved ones know they are OK. The tool was particularly useful as many mobile networks were down and people struggled to reach their family and friends. Those who were in the area got an automatic message from Facebook, prompting them to mark themselves as "safe". Those not in the region were able to access the safety tool to check which of their friends were there, who had marked themselves as "safe", and who were yet to do so.

4. Ola Cabs

In November taxi service Ola Cabs launched a free rescue boat service for the Chennai flood victims. The Ola taxi app, which works on a similar basis to Uber, deployed boats in waterlogged areas based on information provided by the state's Fire and Rescue Department.

Ola Cabs hired professional rowers and fishermen to operate the boats, which could be hailed using the taxi's app. The boats were also used to provide food and drinking water in areas that were short of basic supplies, with both ferrying and supplying services made available free of charge.

5. Airtel/ Paytm/BSNL

Telecom companies across India have been offering free talk time to their customers in a bid to ensure that everyone can remain connected with their loved ones during the floods. Airtel, BSNL, Vodafone, RCom and Aircel are among those offering free time to customers in the flood-hit regions. Apart from offering free time, mobile networks also provided users with free internet data of up to 100MB in some instances and an extension on monthly phone bills.

Social media users quickly began taking advantage of these offers, with volunteers offering to top up the phones of those who are stranded if they sent them their phone number.

6. Vodafone

Vodafone India took their efforts one step further than other mobile networks during the Chennai floods by launching a service to help find missing people. Through the 'Trace Your Loved One' program, customers were able to call a special helpline and provide the phone number of the person they were attempting to track down. Vodafone would then send them a text within two hours with the details of their loved one's last tracked location.

7. Google

Google launched a Crisis Response tool that rounded up everything people needed to know about the disaster region, including useful emergency numbers. It also listed useful messages on Twitter and provided weather updates for the region. Information on staying safe and maintaining hygiene during the floods was issued, alongside a list of crowdsourced places and people offering shelter to those whose houses had been flooded.

8. Zomato

Restaurant-finder and delivery service Zomato launched a 'Meal for Flood Relief' offer. Any time someone bought a meal for a flood victim in Chennai, Zomato added another meal to the donation. A number of restaurants agreed to take part in the initiative and the service gained nationwide popularity. Within a few hours people had bought 15,000 meals for Tamil Nadu's flood victims, with Zomato delivering 30,000 meals after matching each donation.

9. Skype

In an attempt to help connect Chennai's flood victims with their loved ones abroad, Skype made international calls to landlines and mobiles in Tamil Nadu free of charge. Anyone based outside India was able to call their friends and family in the flood-hit region to check on them, free of cost, through Skype. The organisation's blog also posted instructions on how to make calls to landlines and mobile phones from a Skype account.

10. Lookup app

Messaging app Lookup partnered with India's largest youth volunteering organisation Bhumi to round up volunteers who could pick up clothes and other essential materials from people living in different parts of Chennai. The donations were then handed out to those who needed it most. People were able to easily chat with Bhumi volunteers through the Lookup app, share their pick-up location, and have their donations picked up straight from their doorstep. The service provided useful during a time when few wanted to venture outside.