There's an art to writing stuff like that, really. A few mods do it automatically (I believe Castparty will send a /party chat for you, and Serenity is mentioned in the threat), but the best ones are homegrown and customized. Invidiously has some good answers to choose from: "%t, your subscription to Life has expired. Would you like to renew?", "Warriors now have a Feign death. It just requires a Priest reagent, right %t?", and "Now ressing %t. Please don't anyone else try because we could end up with half each, and that would just be awfully messy" (for the noobs, the "%t" in a macro just substitutes the target of your spell; in this case, the person you're rezzing).
But some of the best text macros aren't even for rezzing-- tonight I had a mage in the party that cast Polymorph: Pig with the simple "Water into wine, enemies into swine." And warlocks go crazy whenever they summon people-- I've seen paragraphs of text coming from them, everything about who to call if this summon goes bad (a lawyer, obviously) to "Click on this portal to summon someone to do your job for you!" (that one comes from a mod, I believe, but not one I've used). Some warriors (I used to do this, in a previous MMORPG) even shout out a macro when they're pulling something, just to make sure the party is ready.
For my characters, a normal "Sheeping %t..." or "Rezzing %t..." seems to work just fine-- it's quick, utilitarian, and to the point. But some people go all out, and I do chuckle when I see the good ones. What do you think-- waste of screen space or fun way to keep other players informed? And of course, what are the best ones you've seen?