FCPX Free Downloads
Alex Gollner of Alex4d has a growing archive of free FCP X filters, effects and colour grades that you can download from his site. His latest batch is 11 colour effects including gamma, gradient colorise, colour reduce and an OpenEXR tone map. His post also includes info on how to make the most of the filters.
Oliver Peters has a five part blog series working through different filters, transitions, effects, colour grades and third party plugins that can be used in FCPX. If you’re using FCPX a lot, it definitely worth checking them out.