On 22 February, the social networking site Twitter reached 500 million users worldwide.

Given its popularity as a communication and marketing tool, Twitter is also becoming a place where travellers can find bargains, plan trips and seek customer service when something goes wrong.

Spot last-minute deals
Many airlines tweet deals, with JetBlue (through its @JetBlueCheeps feed) and Virgin Atlantic providing the most worthwhile offers. To see these discounts, follow your favourite airlines, or at least the ones you fly most frequently. You can also check out Wanderlisting, a website that compiles the most worthwhile deal-related Twitter feeds from airlines, hotel and other industry experts.

Sadly, few hotel chains have fully embraced Twitter as a multi-purpose communications tool. Honourable exceptions include Fairmont, Marriott and Starwood (a chain that includes the Westin and Sheraton brands), all of which post interesting deals and also address customer feedback.

Get airfare deals relevant to your local airport
FareCompare, a website that tracks ticket prices, offers Twitter feeds tailored to specific US airports and promotes price drops on fares to thousands of destinations worldwide. For instance, its feed @flyfromPHL offers deals on flights departing from Philadelphia's International Airport. Find your hometown airport in the drop-down menu at FareCompare and click on the Twitter handle to follow it.

Use Twitter's search tool
Get the real-time scoop on your destination by using Twitter's search tool. A quick search for “Miami hotel deals” recently yielded a few relevant tweets, including one from Valarie D'Elia's travel blog, which detailed a $199 a night offer at the city's Shelborne Hotel, via the site Secret Rates. Meanwhile, searching on the term "Vegas spa" turned up a tweet about the "Crazy8" package at the Westin Las Vegas, which included a discount of 20% off treatments at the property's Hibiscus Spa.

Seek real-time customer service
The occasional snafu is unavoidable in air travel, and Twitter is increasingly one of the top channels airlines use to provide customer service. In 2011, Delta Air Lines set the industry bar high by committing to answer the typical passenger's tweet within 10 minutes and address customer service problems within 24 hours, via @deltaassist. A full list of airlines is available at Wanderlisting, including social media champs Southwest and Virgin America. A few of the non-US airlines that have embraced Twitter wholeheartedly include British Airways, Cathay Pacific and Air New Zealand.

Check the reputation of an unfamiliar airline or hotel
User-review service Eezeer trawls the recent tweets from about 650,000 verified Twitter accounts to help travellers uncover opinions about an unfamiliar airline or hotel. To run a search, enter the name of a carrier or hotel into the Eezeer website or into one of its free apps for Apple and Android devices.

Sean O'Neill is travel tech columnist for BBC Travel