Inqlude provides a comprehensive listing of all existing libraries for developers of applications using the Qt toolkit. Inqlude is run by the community and open for contributions.
Image Effect Library for KDE
Blitz is an interm image effect library that people can use until KDE 4.1 is released. KImageEffect, the old image effect class is being dropped for KDE 4.0 and the replacement, Quasar, won’t be ready until KDE 4.1. Blitz gives people something to use in the meantime.