Process Engineering and Simulation Software
Cape-Open Organisation
ASPEN Plus, HYSYS, Aspentech
ChemCad, ChemStations
COCO, Amsterchem
DESIGN II, WinSim
gProms, Process Engineering Systems
PRO/II, SimSci (AVEVA)
ProMax, Bryan Research & Engineering
ProSimPlus, ProSim
Symmetry (formerly VMGsim), Schlumberger
UniSim, Honeywell

Column Internals Vendors
ACS
Envimac
Jintai
Hat
Koch-Glitsch
Lantec
Montz
Pall Ring Company
Raschig
Rauschert
Sulzer Chemtech / Shell Global Solutions
Sutong
Tray's R'us
Vereinigte Fuellkoerper-Fabriken
Zehua

Tower Scanning
Bulander-Esper
Nuclear Scanning Services
Quantum technical Services
Scanning technologies
Tracero
Tower Scan

General Chemical Engineering
Periodic Table
EFCE European Federation of Chemical Engineers, Institution of Chemical Engineers (UK), DECHEMA, VDI, KIvI/NIRIA, SGVC American Chemical Society, American Institute of Chemical Engineers
EFCE Working Party Computer Aided Process Engineering
American Petroleum Institute
National Petrochemical and Refiners Association
United States Patent and Trademark Office
American National Standards Institute
ASTM
CACHE A learning community in Chem.Eng.
Chemical Engineering Community

Separation Technology
Fractionation Research, Inc.
Separations Research Program
EFCE Working Party on Fluid Separations
Distillation and Absorption conferences 2014, 2018, 2022.
Kister distillation symposiums 2013, 2017, 2015, 2019, 2021, 2022, 2023.
Frank Wijn distillation pages (from archive)
Google Index of ChemSep.Org on 'Efficiency'
Google Scholar search on 'nonequilibrium distilation'

Books/Tutorials
Separation Process Principles by Seader and Henley
PhD Dissertations under Ross Taylor
The Art of Distillation by John French
Wikipedia: Distillation

Thermodynamics
Data and Property Calculation Websites - Mansoori
DECHEMA Detherm / Dortmund Data Bank (for example data)
Azeotrope tables and other information on wikipedia
DIPPR 801 Design Institute for Physical Properties
Korea thermophysical properties data bank
NIST and PubChem chemical databases
ThermoML
RefProp (see this paper) and CoolProp
OLI Systems
Vapor-Liquid Database - Shuzo Ohe
Center for Energy Resources Engineering
ChemEssen Mol-Instincts Database

Numerical Programming
BESIRK Fortran DAE Solver
Code::Blocks Cross-platform free Integrated Development Environment
Gfortran Cross-platform free fortran compiler
Fortran recources for windows and linux
Fortran and C/C++ Mixed Programming
Netlib numerical codes repository
Octave, a *free* MatLab clone
Scientific Software - Debian Linux
Sundials Nonlinear and DIfferential/ALgebraic equation Solvers

Open Source and Linux
Veusz free scientific plotting tool compatible with ChemSep
Lazarus IDE for free pascal to build GUIs
CPAN Perl Repository global source for Perl modules
Delphi expert tools
GNU free software
Python and Python tutorial
O'Reilly computer software books
SlashDot.org keeps you up to date
SourceForge is a open source repository
DOS/WindowsXP commandline overview