I originally made my own little system for keeping track of my money and worth, and I told some of my alliance members about it, and they sounded interested, so I did a complete overhaul of my system so it would be viable for general use.

My handy dandy accounting system to keep track of all of your funds!
Farmer Kane's Accounting System.xls
Features:
-Tracks Gold across characters
-Helps Track Material Price Changes
-Tracks Total Material Worth
-Tracks Overall Worth (Gold + Materials/Runes)
-Tracks Overall changes in net worth
-And Much more!
I think it's pretty straight forward, but if you have any questions on how to use it, feel free to ask!
It'sa big ol' excel spreadsheet workbook, be sure to note that there are 4 sheets, to go to the next sheet, hit the different tab near the bottom of the excel window. Start on the "Totals" page by entering the date (which will be automaticly entered in the next sheets), Enter your character names, and under them, the amount of gold that they are carrying, as well as the amount of gold in your storage. You can stop here if that's as complex as you want to go.
If you want to keep track of your materials, go to the Material Prices sheet and enter the merchant buy prices (the prices the merchants will buy from you) in the respective cells. Next, go to the Material Amounts sheet and enter the amounts you have. You can now look at the Material Values sheet to see the value of your amounts of materials. Once you've entered the current price and your amounts, the Totals page will be updated with your total Gold Value, Material Value, and Net Value, as well as the change from the previous entry if applicable.
Enjoy!
PS. One problem others have found, depending on your system, the date format may get changed to UK or US, if it's one you don't want, just highlight like the first 100 date cells in the totals sheet, right click, hit format cells, then go to the numbers tab, then find date on the list, and change it to what you want.