Bless WowInsider's heart (or Wow.com as they're now called). They are a great source of information. They compile so much from so many sources. It's just a shame when they miss little things. Like they're little post about Essential addons for raid leaders. The very first mod they list is for Deadly Boss Mods (good). And as is mentioned, it's kind of a necessity for all raiders. But the most important part of that suite for a raid leader doesn't come from Curse as is linked on their site.
Oh no... the most important part comes from the Deadly Boss Mods downloads page. They're two extra packages called "Spell Timers" and "Raid Lead Tools". Let's see the description, shall we?
"DBM-SpellTimers is a small but powerful addon that uses DBM timers to show spell cooldowns from raid members. It is fully configurable through a simple GUI so you can easily add new spells."
Want to know when Heroism is up? Or how about who cast Rebirth, and who's still on cooldown? Or how about anything with a significant cooldown? (Yep... even portals. lol.) Yeah, kind of important for a Raid Leader to know. Go get this one.
Raid Lead Tools
"Raid Lead Tools uses the DBM API (especially the kill/pull detection) to manage your raid and DKP. You can export tracked raids to eqDKP with just a few clicks!"
Now, I've actually used CT Raid Tracker for this functionality. (Found here... used to be hosted on Curse.) But it sure sounds like a useful Raid Leader Mod to me. :)
Point being though.... the Spell Timers are WAY better than having to ask, "Whose Battle Rez is up?"
Edit: I didn't even mention the best part of these additional mods. Not sure which one it is, but one of them gives a mass invite to all guildies. Saves a ton of time when you have exactly 25 (or less) on. :)