1000sounds recently released Volume One, a free 543 patch Omnisphere 2.5 library.
The patches in this Volume One release only use core Omnisphere sound sources and effects. A future release is planned that will integrate both Omnisphere Sonic Extensions and Keyscape sound sources and effects. Limiting this initial release to core Omnisphere sounds and effects makes it more accessible to everyone.
Mod Wheel and Aftertouch: These patches were designed with expressiveness in mind. Most patches have parameters mapped to both of these controllers. Hopefully your MIDI keyboard has both.