Which Rank Does What
Displays a grid of guild ranks versus guild permissions, including permissions for each tab in the guild vault. This information is primarily displayed by Blizzard's builtin Guild Control button on the guild window's Info tab, but that button is only clickable if you are the guildmaster. D'oh! This addon is intended for the rest of us.
Use /wrdw to toggle the window on/off. There are some very minimal options available through the usual Interface menu, one of which makes the Guild Control button usable by everyone to display this window.
There are so many guild permission flags these days that I've shrunk the main window and added "previous/next" buttons at the bottom.
The vault tabs running down the side of the window can easily get in an incomplete state; this is due to the way the Blizzard API works, and there is no workaround (e.g., proximity is required). If this happens to you, /reload. The simplest way of ensuring correct display data is by first opening the guild vault once.
Right now this display is read-only; that is, you cannot use this addon to actually control guild permissions. It is doubtful that I'll add functionality to check for guildmaster status, because the builtin Guild Control UI is already so much improved in Cataclysm.
Bugs, problems, pizza, whatnot: leave a comment or file a ticket at the Development Site link above. If you have downloaded this addon from anywhere other than directly from Curse or WoWInterface, then it is outdated at best and infected with viruses at worst. Clone sites not only leech bandwidth, lately they've been adding malware as well. Get your addons from safe sites with a good reputation!
If you're a reasonably proficient speaker of non-English languages, any translations you can do would be welcome! Just make changes at http://www.wowace.com/addons/whichrankdoeswhat/localization/ and then send me a PM to notify me. I can offer nothing in return except public credit, my appreciation, and a beverage of your choice if you're ever in town.