Re business usage: I've found https://zoom.us/ https://zoom.us/ to be a good alternative to Skype for conference calls and screen sharing - it's freemium, free

Re business usage: I've found https://zoom.us/ https://zoom.us/ to be a good alternative to Skype for conference calls and screen sharing - it's freemium, free for calls up to 40 minutes (after which you just re-call everyone). Quality of the call and software seems to be a lot better, maybe that's just because corporate firewalls don't try and do weird stuff to it though :D