Foreign Exchange Market

Online Currency Trading

• Forex.com
• Forex.com: Forex Pro
  
• Fxstreet.com
• Fxcm.com

Real time financial market information

• eSignal.com
• Bloomberg.com (Currency)
• Yahoo! Finance (Currency)

Other ...

• FactSet.com
• HyperFeed.com
• FTInteractiveData.com

Encyclopedias

• Investopedia
• Wikipedia: Financial Mathematics
• StockCharts: Glossary
• MathWorld Wolfram Research