This site offers general information on the WAAS service provided by the U.S. FAA. http://www.faa.gov
For realtime WAAS satellite corrections and performance:
To subscribe to the SatNav newsletter notification: http://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/techops/navservices/gnss/library/satnav/
ESA EGNOS Web Site
This site contains information relating to past performance, real-time performance, and broadcast schedule of EGNOS.
ESA main page: http://www.esa.int/esaCP/index.html
EGNOS page: http://www.esa.int/esaNA/egnos.html
EGNOS for Professionals: http://www.egnos-pro.esa.int/index.html
MSAS Information
Kobe Aeronautical Satellite Center in Japan provides some info on MSAS.
Finding SBAS Satellite Elevations
The following web page allows computing elevations of satellites above horizon from any location in the world: http://www.lyngsat.com/ (Java plug-in required)
WAAS PRN 135 WAAS PRN 138 EGNOS PRN 120 EGNOS PRN 126 EGNOS PRN 124 MSAS PRN 129 MSAS PRN 137 GAGAN PRN 127 Inmarsat 4f1 is no longer broadcasting GAGAN corrections