Microsoft Lync 2013 (beta)
Lync took the longest to get installed. That might be because it’s still officially in "preview edition" or because we were using an earlier version of Microsoft Office and it wants to install the 2013 Live Office version. Nevertheless, the 2013 Windows client still crashed several times and I had to re-install it on a second Windows 7 computer before I could continue testing. Once I got it installed, it was easy to start meetings and share various pieces of content. Lync charges on a per-user basis ($6 a month). It supports iOS, Windows Phone and Android mobile devices.