Foursquare
Check in not only at the event itself, but into indiviual sessions, receptions, luncheons, local restaurants, museums, and other venues. See who else is there, leave tips for other conference attendees, and network via this mobile social app. (Available for iPhone, Android, Blackberry, Windows Phones, & more).
unsocial
This app lets you connect with business professionals in your proximity. It uses geo-location and smart tagging to help you find and be found. (Available for iPhone, Android, Blackberry, & Windows Phones).
BeamMe pro
beamME finds interesting people nearby based on your profile. You can then easily chat, share your actual location or contact information and meet – all from within the app. You can even connect it to Facebook and Twitter to see which contacts are at the event. (Available for iPhone only).
Access social information about the conference you’re attending such as scheduled events, who’s attending the conference, what people are saying about the sessions and the locale, view photos that friends are posting, and chat with other conference attendees. (Available for iPhone, Android, Blackberry, Windows Phones, & more).
Bump
Share all sorts of contact and social network information by bumping two phones together with the app. Just choose what you want to share/send and then hold the phones together. you can then message them through the app as well. (Available for iPhone and Android).
Ustream Live Broadcaster
Stream live video from the event to your Ustream account from your phone. You can notify your Twitter and Facebook social networks as you start your broadcast so that they can join you. You can make your broadcast social by integrating a live Twitter or Facebook feed. (Available for iPhone and Android).
Shhmooze
Shhmooze lets you check into conferences or meetup events and find out who’s interesting based on your profile and theirs. Connect with other attendees by virtually waving to break the ice.
(Available for iPhone and Android).
Free Wifi Finder
This handy app uses your iPhone’s GPS and network triangulation capabilities to instantly locate free Wi-Fi Internet hotspots wherever you are in the world online or offline. (Available for iPhone and Android).