ThinkorSwim also has a great iPhone app. CNBC app is rather good. Also I like FX360 and Forex OTG if you're into FX.
Other good apps: Bloomberg (of course) LoanShark (useful amortization) 1cast (a lot of video news sources) RateWatch (nicer way to get some rates than going to WSJ.com) StockCharts (plenty of technical charts. dont use this much anymore since ToS does good charts) TimeValue (time value of money calc) Options! (blackman/scholes model)
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