Useful web links:

Standard Reference materials
NIST standards
USGS reference materials 
IRMM Belgium
Geostandards Newsletter
Links to various geostandards

Isotope producers
Oak Ridge National Laboratory 
Isotope Products
New Brunswick Laboratory

Conferences
European Winter Conference on Plasma Spectrochemistry in Garmisch-Partenkirchen, Germany, 12-17 January 2003
EUG in Nice, France, 6-11 April 2003
Geoanalysis in Rovaniemi, Finland, 9-11 June 2003
Plasma Winter Conference in Fort Lauderdale, Florida, 5-11 January 2004
Goldschmidt in Copenhagen, Denmark, 5-11 June 2004
7th European Workshop on Laser Ablation in Sheffield, U.K., 13-15 June 2004
9th Conference on Plasma Source Mass Spectrometry in Durham, U.K., 12-17 September 2004
European Winter Conference on Plasma Spectrochemistry in Budapest, Hungary, 29 January-2 February 2005

ICPMS manufacturers
Agilent Technologies
GV Instruments
Nu Instruments
Perkin Elmer
Thermo Elemental
Thermo Finnigan
Varian
LECO
GBC Scientific Equipment

Laser manufacturers
Bioptic
Cetac
Coherent
Lambda Physik
Melles Griot
Quantel
New Wave - Merchantek

Other links
Plasmachem
Martinsdale's Reference Calculators
Isotopic composition of elements (IUPAC)