Since I kicked CT_RaidAssist I'm using T_Raidwarning as a warning system for various boss mob warnings. It got no updates for a while now - so I guess Saroz doesn't work on it anymore. I would love to sea an ace'd version with a Timex depency (t_raidwarning has chronos depency, but worked well with timex) and more supported bosses (ct_ra has the first Zul Gurrub timers etc)
For example, I'm thinking I could code such an AddOn but I'd put the power back in the hands of the player, how it would work is something like this;
/cmd add txt=I'm the Boss and I just did Boomewang!! (Wot? I have a lisp like most bosses in Warcraft.):tmr=30:warn=OMG, Boss just did BoomWang, flee for your LIVES!!!warnend=Boss is about to do BoomWang, omigosh!
Wouldn't something like that work, with a base framework for players to add their own?
< Edit >
To explain it further ... warn would fire as soon as the boss executes his attack, then 30 would be how long it would wait before sounding off with warnend. So if the boss's attack waited 35 seconds, 30 would be a good time.
I don't know how T_RaidWarning works but I've seen CT_Raid do its thing and it does a sort of count down to the "big boss event". Every 5 seconds leading up to the event time you get a new message in the middle of the screen. Not sure how far in advance it starts, about 30sec I think.