SharePoint 2013. Content Search web part.
The content search web part is just brilliant. Not only does it let you aggregate, filter and find content and their metadata. The new way of styling with the new display templates is a huge relieve after all the xslt horror in the SharePoint 2007 and SharePoint 2010 versions.
One word of caution: I learned the hard way today that the Content Search Web Part is only available in the SharePoint Enterprise (on-premise) installation.
I hope that the nice folk @Redmond change their mind about this and also make it available for the SharePoint Standard and SharePoint online versions.
The on-premise feature matrix can be found here:
The online feature matrix can be found here:
Back to the drawing board…