Did you know more than are more than one billion iPhone apps have already been downloaded for your iPhone? (Note: Thanks to Don Bartholomew for the correction) ONE BILLION. So when Apple says “there’s an app for that” they really do mean it. I mean, they’ve thought of everything. Literally.

As consumers, we love apps that help us get organized (Evernote), make informed decisions (Urban Spoon), navigate a new city (Google Maps) and have fun (my new fave, Tiger Woods PGA Tour).

But, as PR pros, what are the apps that we absolutely have to have to do our jobs in this new media age? After a little research and polling a number of PR/social media luminaries who use the iPhone on a day-to-day basis, I identified the following seven “must-have” iPhone apps:

• TweetDeck. Seems to be two camps. Those who love Tweetie, and those who love TweetDeck. But, TweetDeck’s ability to organize multiple groups and multiple accounts makes it a little more valuable. It’s an essential tool for monitoring the brands you represent on Twitter while you’re away from the office.

• Facebook. An unquestioned staple. Like TweetDeck, the opportunity to monitor your brand’s fan pages, upload photos, and add other content on the run is invaluable.

• Bump. A new app, but one that’s gaining popularity by the day. Especially for you PR and social media conference-goers out there. Allows iPhone users to swap contact info simply by touching phones. Really. I’m not making this up.

• Google: Email, Reader, Maps. You need them all. But, you also need the basic search engine and it’s ability to help you find anything, anytime, anywhere.

• Evernote. Are you one of those people who does their best thinking in the car? Then this app is for you. Capture those ideas and sync them with your Mac back at the office. Grab screen captures of white boards after meetings and upload them to your desktop. Or, take notes at a meeting and upload to your files online later. Evernote does it all.

• Stitcher. An interesting new app that, like Pandora, allows you to customize your content. In this case, it’s audio—talk radio, news and information. The likely sources? CNN, NPR, TechCruch, AP, ESPN and a host of other online audio content creators. Imagine creating a content stream of personalized audio (news and information specific to your organization/clients) you could listen to each day on your way into the office. How valuable would that be?

• WordPress. The popular Web blogging tool now has an app for the iPhone (3G and original) and the Touch. Claims to be the only iPhone app that allows you to write posts, upload photos, edit and manage comments—right from your phone. A handy little tool when you need to manage a client’s blog on the go, wouldn’t you say?

Want more? Here are a few additional favorites from a number of PR/digital thought leaders:

Lee Odden, CEO, Top Rank Marketing—Twitterfon, Safari, Google, Facebook, Clicky Mobile,

Sara Masters, communications director, Minneapolis Synod—TweetDeck, Tweetie

Sonny Gill, founder of Community Chat—Twittelator Pro, Facebook

Jason Falls, vice president/director of interactive and online communications, Doe-Anderson—Tweetie, Evernote, Newsstand (RSS), Yammer, Bump

Sarah Evans, principal, SevanStrategy—Tweetie, Things, Facebook, USA Today, esnews, Bump, Air Mouse, Remote, Yahoo, WordPress

Albert Maruggi, president, Provident Parnters/Senior Fellow-Society for New Communications Research—TweetDeck, SimpleMindx, Tweetie, Wall Street Journal, NY Times, Google, Stitcher

Dave Fleet, account director-Social media, Thornley Fallis—TweetDeck, Evernote, Instapaper

Blois Olson, executive vice president, Tunheim—Stitcher, Facebook, Tweetdeck, Google

Ken Burbary, digital/social media lead for Ernst & Young—Tweetdeck, LinkedIn, Facebook, Evernote, WordPress, Brightkite, Google, Yammer, iDrive, NYTimes, tipcalc

Chuck Hemann, research manager, Dix & Eaton—MarketingProfs

OK, now it’s your turn. What would you add to this list? What are the iPhone apps you can’t live without when it comes to conducting business on the go?

Photo credit: Neils Van Eck (FlickR)