When ING's savings interest rates started plummeting, the graph of the rate over the last several months mysteriously disappeared from the website. I contacted customer support but got nothing useful in reply. So I organized a collection of the data I had kept since September 2007. Here is a chart and data series of ING's savings interest rate.
If anyone knows how to get Google Spreadsheets to graph date-series data in a useful way, please let me know.