Some new open-source, cross-platform launchers recently. http://zazuapp.org is another alternative. But it will take them some time to catch up to Alfred and Launchbar (both are really mature and have a fantastic community & lots of extensions), if they ever.
@tafkaf I'd like a discussion here on the development aspects (sinece Devs ultimately need to choose which plugins they'll write for). First of all, cerebro is an Electron app, which some ppl hate due to high RAM usage.
