ETFs 101 by Bob Clark
Discount Broker 101 by Bob Clark
Optionistics – find the options sweet spot for stocks.
Economagic.com gives me access to 1000s of economic data series and charts. Allows for fast and easy creation. FRED (Federal Reserve Economic Data) is another killer site that allows free access to different runs of economic numbers. Between the two of them, if you cannot find what you are looking for, you need to get a Bloomberg terminal.