Well, the Dretch*Storm server has a nice "RAMPAGE" mode which kills all spawns, sets both teams to stage 3 and gives 9 evos / 2000 credits to all players...
Unfortunately, the server operator there (GhostShell+) is a source-code hoarder and so I've had to script this functionality myself as a mode called "Extreme Sudden Death".
It can be tested on S11.Info:8000 calling a vote for "extreme_sudden_death", or waiting for g_extremeSuddenDeathTime to expire (at 46 [minutes]).
Also, S11.Info:8000 runs a revision 894 checkout of the mainstream svn codebase with several patches applied, including the ability to call votes for designate, extreme_sudden_death, and sudden_death.
Anyone who's interested in a copy of the codebase I build to run S11.Info:8000, just ask me and I'll send out a tarball.
Prosper.