I made a web app to help out with guild bounty missions. Its power relies in shared information about bosses between more guilds.
Typical workflow would be:
1) plan a guild mission for the same time when some other guild mission has planned guild mission
2) tell members guild password so they can log in
3) before guild mission start go search for bosses and let members mark their location on the map. Guild master has overview how many bosses are missing.
4) When found enough of bosses mission can be started – guild master checks bosses which guild is supposed to kill and the detail page changes to overview with boss map and last known location – every member can alt-tab to see where the boss exactly is.
There is known bug when location of the boss on the map is not updated – you have to click address bar and press enter to refresh page.
Try it out here: http://gw2bounty.nuc.cz