Use of smartphones and mobile devices has grown at a rapid pace over the past couple years. Just look around the next time you go to a mall, coffee shop, airport, or when you’re just walking down the street: Everyone, it seems, is looking down at an iPhone, Android, or another mobile device.

Recently, the Pew Internet Project found that 83% of American adults own a cell phone, and 42% of those people own a Blackberry, iPhone, or similar smartphone. The study also found that 87% of smartphone users access the internet or email on their device, including two-thirds who do it daily.

That means when people come to your events, chances are good that they’ll have a smartphone or other mobile device with them. Do you have a plan in place to make your events more mobile? Here are four ways to add mobile to your event strategy:

1. Encourage live tweeting

Does your event have a hashtag? If not, then create one. (For example, if you’re hosting a wine tasting next month, your hashtag could be #SeptWine.) Once you’ve got that, promote it to all your attendees, some of whom are likely to be active tweeters. Live-tweeting with a hashtag allows attendees to meet each other more easily — and just as important, to alert conference organizers like you if there’s anything that needs fixing. (A bonus is that tweets about your event will spread the word to those beyond the venue walls.) A tool like Hootsuite makes it easy for you to sort tweets so you don’t miss any that include the hashtag, and the Constant Contact Event Marketing tool allows you to create a hashtag and promote it from your very first communication about the event.

2. Check people in on the go

As an event organizer, you likely look for ways to minimize costs and minimize the paperwork. The Event Check-In App from Constant Contact helps you simplify the check-in process, and do it all on the go too. You can easily search the registration list and check people in with one click. It syncs directly with your Constant Contact account, so you can be confident that anything you do on your mobile device will be reflected when you get back to your desk and use your computer.

3. Let people check themselves in

Encourage people to check in on location-based services like Foursquare, Gowalla, or Where. This is a fun way for attendees to share that they’re at your event with their friends. It also lets your attendees share info and tips with each other. These services even allow you to add a unique special offer, such as a free beverage (if there’s a cash bar) or a piece of swag. Even better, Foursquare has begun rolling out enhanced features so people can check in to specific events, not just the venue where they’re taking place. Keep watch for this feature to be expanded as time goes on.

4. Use QR codes

You’ve got all those people together in one place. Now use that to your benefit to build your email list or communicate important information. Convert your website URL or Join My Mailing List page to a QR code and post it throughout the venue. People who are hip to the image they see will be able to easily scan it and take the action you want them to. And those who don’t know what the image is will be curious enough to ask and learn more.