An addon I am looking for, simple one.

[Jigain]

Half a gigabyte for addons? You really need to find out which of them causes memory leaks and remove it.

I use between 50-90 addons per character (depending on class, professions, primary use and so forth) and I've never, ever, EVER seen my memory usage go above 50mb. Unless one or more addons are broken and "memory leaking", as it's called, you should only see 500mb usage if you're running the game with ~500 or more addons running.

[voodoodad]

Let's try to keep it civil, folks.

yeah, I know... ME telling people to keep it civil...

/sigh...

I have zero credibilty...

Actually you can use Weak Auras (http://www.wowace.com/addons/weakauras/). crate an aura to check for certain debuffs and then crate a message to a specific channel when this event happens.

Little more complicated and not just install and go. Also of memory usage is a concern for you, then this mod might not be one you would want. Unless a mod is poorly written and has memory leaks you shouldn't really be affected other than initial load time (logging in your character).

Mods scanning for debuffs on the entire raid (like a Power Aura checking for ANY magic, poison etc. non-specific spell will also use up more CPU than the average addon.)