. Historical FX Rates: http://oanda.com/convert/fxhistory
2. Historical Stock Prices: http://finance.yahoo.com/q/hp?s=yhoo
3. Recent LIBOR rates: http://www.bba.org.uk/public/libor/
4. Some Implied Volatilities: http://www.ivolatility.com
5. Delayed Commodities: http://www.liffe-commodities.com/
6. US Fundamentals: http://www.sec.gov
Of course, I also like some economic data:
UK: http://www.statistics.gov.uk
US: http://www.census.gov , http://www.bls.gov , http://www.federalreserve.gov , http://www.ssa.gov , http://www.treasury.gov