XMM SSC (Survey Science Centre) pages

http://xmmssc.irap.omp.eu (includes documentation on catalog columns)

3XMM-DR7 data tables

3XMM-DR5 footprint (MOC files)

Note that these are preliminary files computed from combined images for pixels that have at least one count in them, hence with small gaps; in future there will be more compact files computed from exposure maps.