I have mentioned this great addon once before, Boss Notes (back in Sept 09). Those guilds going up against Putricide you might find it helpful. Saves alt-tabbing to whichever website you use.
It can learn boss’ abilities (make sure you turn this on; it’s off by default). This gives you their spells (with tooltips), in a handy notebook, into which you can also write your own tips and reminders. Includes simple written strategies for all the older bosses, too, including 5-mans, and allows data to be shared amongst your guild.
It has a new feature, called Rules, which I haven’t tested:
The Rules module allows the definition of custom encounter rules for notifications, timers, raid target icons and yells. In a nutshell, it supports a roll-your-own boss mod approach to encounters which is completely in-game and does not require programming. Instead, declarative rules are used. The rules module is not intended to replace your current boss mod. Rather, it provides bridges to common boss mods that integrate your custom rules with the regular display provided by your boss mod.