As mentioned, FXE. Other currency ETFs by rydex: http://www.currencyshares.com/ Tradable currency funds by rydex: Dynamic Strengthening Dollar + Dynamic Weakening Dollar http://www.rydexfunds.com/ourproducts/fund_profiles.shtml
Take your pick... 1. FDPIX - Falling US Dollar ProFund RDPIX - Rising US Dollar ProFund 2. RYWBX - Rydex Weakening Dollar Fund (leverage 2:1) RYSBX - Rydex Strengthening Dollar Fund (guess what, also 2:1) Launching soon (papers filed with the SEC): 3. UDN - PowerShares DB US Dollar Index Bearish Fund UUP - PowerShares DB US Dollar Index Bullish Fund All of the above track the USDX on NYBOT.