Font Awesome is an iconic font designed for web UIs. It's a full open source suite of pictographic icons available with examples and documentation.
During the QML network lecture at QtDD, Jeremy Lainé has noted that icons based on Fonts Awesome are useful for optimizing network usage, especially ones with high latency. While I have never used them I knew the technique which seems to be quite popular among web developers.
So I came to related idea. How about adaptation of the Font Awesome icons for KDE? Obviously number of icons expected by KDE themes is much larger, but there's a way to start. It would be awesome (!) if someone implements that to show power of QIconEngine...
Of course the adaptation would only be semi-automatic because mapping is needed between Font Awesome naming and freedesktop.org naming.
Further ideas if you dare for more:
At visual level there is a bit to think about too - putting taste aside, by popular opinion monochrome (or at least visually simplified) icons give apps fresh and "cleaner" look, allow to put focus on content. Moreover, the web uses monochrome icons a lot these years, the world is tired of skeuomorphism, Vista glossy style is dead...