From South Wales Bouldering Guide Wiki
Martin Crocker And Oliver Keynes have produced their own set of excellent PDF's covering a number of beautiful areas to climb at.
Martin Crocker has his own website who in his own words is "a long-time British climbing activist and pioneer, a guidebook author, and a local access campaigner." On his website you can find a number of excellent resources, articles and PDF Guidebooks of the Brecon Beacons which can downloaded from his Downloads page. In downloading and using his PDF's he asks if you can please donate to your local search and rescue team.
Oliver Keynes has created some excellent PDFs of several areas that can be found throughout this wiki.
For easier access a list of which can be viewed below.