Reference websites for GNSS status

For GPS status
http://www.navcen.uscg.gov/navinfo/Gps/ActiveNanu.aspx
For WAAS status
http://www.nstb.tc.faa.gov/RT_NPACoverage.htm
For GLONASS
http://www.glonass-ianc.rsa.ru/pls/htmldb/f?p=202:20:5054833760327974336::NO:::
For EGNOS
http://www.egnos-pro.esa.int/IMAGEtech/imagetech_realtime_html.html

Trimble's planning software
http://www.trimble.com/planningsoftware_ts.asp?Nav=Collection-8425