Google has just added Android screen mirroring to Chromecast last month, but what if you didn't have the streaming HDMI dongle and only wanted to mirror to your computer? Koushik "Koush" Dutta's AllCast app and receiver duo might be your savior, but only if you had a Nexus 5. Soon, however, it will work with almsot any Android device you have in your hand.
AllCast is Koush's all in one Android streaming solution, encompassing both streaming select pieces of media to mirroring the whole screen. Last May, Koush announced a Chrome browser extension of his AllCast Receiver, which basically meant turning any computer into a makeshift Chromecast plus TV combo. In theory, you would be able to send your media or your screen to Chrome running on any computer (as long as they're on the same network of course). In practice, however, it's not so simple.
Koush notes that there is still a bit of lag, which means it's far from perfect yet, though that's not really unexpected. Given how those apps are available for free and doesn't require the purchase of new hardware, it might not be a bad tradeoff. That said, this new feature does require an update to the app and Koush has not yet indicated when he will be pushing that out.