Scrybe Labs has launched Convofy, a new private social network for companies. Like other collaboration tools, including Yammer, Convofy has a real-time message feed on which you can chat with colleagues and upload files. (You can also add files or Web links to a desktop drop-box that's always on, without having to open the app.) In the app, you can view an active to-do list, project milestones, and who is online.

What makes Convofy different from the competition is the ability to do real-time annotation of Web pages and files, including PDFs, Word documents, and Excel spreadsheets, right in the app. When you click on a thumbnail of a PDF in the message feed, for instance, the full file will pop up in a new tab. Then, you can use a Markup tool do things like highlight text and make comments.

Unlike Yammer, which is based online, Convofy is a desktop app that you must download. The basic version is free; you can upgrade to a premium version with more administrative controls for $5 a month. Convofy also offers a stripped-down mobile app that works on most mobile devices.