I've been using KiCAD for my schematic capture and layout tasks for about a year now, and I find it to be the best free tool that I've seen. In the interest of making it easier to share my projects, I've put all of my KiCAD libraries on github: https://github.com/mogar/KiCAD_libs
I tend to organize my libraries in pairs. One library of symbols and one library of corresponding modules. That way I know where to find the footprint I'm looking for.
I started out using a library that had been created from the SparkFun Eagle libraries. This has worked pretty well and has a lot of common components, but footprints are often messed up. I've been fixing them as I run into issues, but definitely check all footprints from the library before you use it.
The other libraries have parts that I haven't found in the SparkFun library. Those libraries are better maintained, but I still suggest you double check everything before using any of those parts.