Some people want to see what they sold and what they made money from, I personally just want to see the net results, so this add-on is perfect for me.
There are some caveats to this add-on though and I will show you some of them right now.
So this is the basic layout of the add-on. On the bottom are tabs so you can go through the different tabs on the bottom of the page allowing you to look at data for the week, day, session or total overall. I find the day and week functions to be particularly useful because it lets you cleanly keep track of your revenue and expenses. The week function resets every Tuesday, which I think is great to coordinate with server resets. It also lets you keep track of spending per character, because sometimes you want to just look at your bank alt and not your wasteful main :-P.
Since this is just a basic spreadsheet add-on that keeps track of all the money that goes in and out, there are some flaws to note.
If you look at this row, you'll see that I had about 80k g worth of Mail “Expenses”. This clearly will never be the case unless you buy things COD. This is money sent between alts for the most part, and since (presumably) all the mail was recorded, it was also shown as revenue. If you want to find how much you made for the week from selling things at the auction house subtract Mail Expenses from Mail Revenue. In this example it's 117,614 - 80,000 = 37,614, so I made 37,614 in the mail from AH.
Also from this screenshot you may notice that there is Auction House Revenue. Not really sure what they mean by that, because most of the AH income is accounted for in mail. Like I said not the most accurate or detailed addon, but it gets the job done.