Windows and OS X: One of the more cumbersome elements of video chatting is that it isn't always as simple as connecting with another person and talking to them. It can fail to connect and you can often try to reach someone without knowing if they're available since many people just leave their normal status as "away." QuicklyChat aims to solve those problems with a simple push-to-talk process.
At first glance, this may seem like a bad idea: someone can push a button and suddenly you're up on their screen. This wasn't designed for people walking around their homes, but rather around the office. If you need to get ahold of someone quickly, you can just click their name and you'll be talking face-to-face in a matter of seconds. This is convenient if you need to ask a coworker a quick question but don't necessarily want to walk across a large office to do it. (On the other hand, that might be in your best interest depending on the situation.)
Users can set status to let others know whether they're available to be contacted (green), should only be contacted if it's important (yellow), or not be disturbed unless it's extremely urgent (red). I think this would work better if these statuses didn't just indicate but rather served a function as well. Perhaps green could allow instant chatting, yellow could require the recipient to approve the incoming request, and red would prevent requests. That does reduce the quickness of it all in some circumstances, but it would be nice to have some sort of do not disturb mode available without the need to quit the app.
QuicklyChat is also pretty rough software at the moment, but that's to be expected because it's a beta. While it is imperfect, it is a cool and useful idea if used in the right situations. Again, you probably don't want to set this up in your house so people can just see what you're up to whenever they feel like pushing a button. That said, to each his/her own.
Quickly Chat (Beta)