Online banking could greatly simplify financial book keeping, if only the web interfaces the banks provide wouldn't be lacking even the most basic functionality for this task. Rather obvious requests such as "show me the temporal evolution of the overall balance on my bank account for the past two years" or "let me look how much cash I drew from the ATM in XYZ avenue in May 2010" are well beyond the capabilities of the online services of any major German bank.
C't 4/10 discussed various possibilities to approach this problem in a user context. A basic perl script for downloading the transactions from an account with Deutsche Bank was presented as example. As I'm a customer of Deutsche Bank, that was just perfect. ;)
The script is very easy to configure, but all you get after downloading the transactions is a list of entries, and you still haven't got a clue when and where you have spent all this money.
A graphical representation would certainly help ... and can easily be obtained by some bash basics and gnuplot magics. Magics? Well, the following plot shows two features of gnuplot which are not as easily attainable with other programs: the data are plotted vs. date and cumulated on-the-fly.