Haystack Search - Haystack helps you make the most of your time, by searching all your files and documents in the cloud in one place. It's been built for privacy from the ground up, so your data isn't stored on a server, just your computer.

Frysbe - Frysbe: Make global friends at random and the fling app comes up with features to send messages to strangers from every corner of the world to expand your social circle.

MailJack+ - Send PDFs as postal mail

PenPal World - Connect with people all over the world

Paperkit - Create and download custom graph, lined, or dot grid paper

Unbordered - Unbordered app comes up with features to help you in finding the perfect language practice and exchange partners so you can practice foreign languages right through your mobile phone.