I made it a new project, for 50 slots and over: http://www.planetminecraft.com/project/100-automated-bank-system-50-slots/

Minecraft automated Bank system, with 10 "bank accounts" (storage units)

Well, were to start off.

I decided i wanted to see if there was some nice automated storage devices out there, and there was, for up to 3 carts. and all the one's with more was buggy as hell, theres one here called "automated minecart storage" but its so buggy and needs a restart function all the time. And asides from that, the place the minecart stop's so you can collect or store, is just plain stupid ( no offense to the maker).
whats even worse is people calling things "automated storage" and it realy isnt automated its just a good organized system of chests.
as of yesterday my knowledge of redstone was crap, but i decided to sit down and learn, its easy and quick. and you get what you want in the end.

So far it is for 10 "bank accounts", and they all work without fail. theres a "failsafe" or moron lock or whatever you want to call it, but i cant get it to activate as fast as i want, and one of my friends couldnt help him self but push alot of buttons fast, but you realy need to try to ruin this, to be able to.

To turn on and off circuits to return the cart's to they're designated station's, sticky pistons is used to block redstone circuits and toggle the rail's until its toggled one last time before its back to its designated storage position, and resets the system. the first rail doesnt use any detector rails to change anything because it doesnt need to.

The pictures will most likely speak for itself to those with a bit of redstone knowledge, to the cheapskates, im sorry at this moment since im not releasing a world save or a schematic. i will upload them, some time after we open our server to the public.

More info is that the entire vault will be protected by bedrock, as well as the buttons to call minecarts. admins or people with the rights to enter through /warp plugins will be able to work the bank. but the station here is just simple and will be changed, to have one "send" back button on each side so that the ones working the bank can send back the minecart if the person withdrawing or depositing items forget to. and to be able to see that there will be an indicator lamp,

there's a couple of more things i would like to add. for example im adding 2-3 more layers, so 20-30 more storage units, wich will all go to the same terminal.

'm sorry that i tend to over explain here and there, but i guess its the screen shots and what it really is you guys was here for.

Update 1:
Things take a while, and i had a computer crash a few days ago, and stupid as i am, all the backups was on the second partition on the same harddrive as the server (stupidity), and then the HDD crashed.

Been doing some work, and been busy so no new screenshot yet, but it has been updated.
so i release the 10 slot system now, first of all so i get a third backup, and id like some idea's on how to optimalize the system as it is now, and add that to the additional layers and shit im working on now.

Thank you, Ohjeey.

Additional Notes

its allowed to come with constructive criticism , but this is as compact i could make it, when the system is fully fixed with 2-3 more layers of storage units, it will be easy to add even more with almost only copying with for example, MCedit, and very basic redstone wiring.

As the server im admin on will be a RPG kind of server, this system is worth more than diamonds, as it adds "interactions" and that is exactly what we want.