Colorbrewer is a great resource for visually pleasing gradients that can be used for mapping. It was already possible to use color brewer ramps in QGIS but it was necessary to create the ramp with the final number of classes in mind.
That’s why I sat down and created continuous ramps from the Colorbrewer data:
If you want to use them, just import the following XML file into QGIS Style Manager: https://github.com/anitagraser/QGIS-resources/tree/master/symbols
For a big selection of point, line and polygon styles check “QGIS symbology set” by S.S. Rebelious.