Guild Bank - Incoming Funds

I was disappointed when Blizz didn't give us the option to do some sort of 'opt in' tax to donate funds to the guild bank. That being the case, i am hoping to find something to fill this slot.

It -seems- like it'd be pretty simple to impliment, seeing as there are many addons out there that keep track of incoming gold, out going gold, expenses, etc.

But basically, what i would like to see would go something like this:

It would keep track of incoming gold. Per session, or perhaps per manual reset - some sort of 'reset' button for if a player would like to keep track of thier incoming gold for more than one session if they cannot make it to a bank to submit their donation. (LootHog's 'clear' button comes to mind.)

It would allow the player to determine how much they'd like to donate. 1%? 1.5%? 4.25%? It would keep track of this amount in conjunction with their incoming gold. Thusly, if i made 500g in one day (oh, to dream...) and have my preferences set to 1.5% donatation amount - it would tell me that i am due to submit 7.5g to the bank. (Forgive me if my math is off. It probably is. I suck heartily at math.) There could also be an option if the total net in the session is a negative amount, indicating that perhaps a donation should be skipped that day.

I realize that this'd be an 'honor system' addon. I don't expect that it'll be keepable-trackable by anyone except the player. It'd also, of course, be completely opt in. If I don't feel like donating for a week straight because i am saving up for something, that's perfectly fine. I simply don't donate the indicated amount. Nothing should be done automatically except the math. No auto-donating while at the guild bank, for example.

Basically, I have a very good solid and supportive guild, and we feel that something like this would be ideal for our particular group, and we'd love to see an addon written up for it.

Thanks for reading!

If you tell us what addons you currently use to track gold difference in a session I'm sure it'd be a fairly simple hack to add another line showing you x% of that. Beats reinventing the wheel, that's for sure ;p