Useful links

An online tool for caluclating the absorption in a capillary sample: Compute X-ray Absorption (anl.gov)
An attenuation length calculator: X-Ray Attenuation Length (lbl.gov)
Programs for converting powder diffraction data file formats: PowDLL (uoi.gr) and 11-BM Resources: The CMPR program (anl.gov)
Malvern Panyltical's Knowledge centre with technical and application notes: Malvern Panalytical's Knowledge Center | Malvern Panalytical and recorded training and sales events Malvern Events - Live Events, Recorded Events and User Training | Malvern Panalytical
A comprehensive set of notes on all things powder diffraction from Jeremy Cockcroft and Paul Barnes Course Material Master Index (ucl.ac.uk)
Structure refinement software: FullProf Suite Homepage (ill.eu) , EXPGUI - A Graphical User Interface for GSAS (anl.gov), GSAS-II - Crystallography Data Analysis Software (anl.gov) , Jana - Crystallographic Computing System (fzu.cz), TOPAS-Academic (paid)
Topas Tutorials: Durham Topas Tutorials Wiki: Topas - Topas Wiki (dur.ac.uk) and Forum: Topas Forum (dur.ac.uk)