Anything. I rarely see ANY scripts and since I'm so poor (read=lazy) at making them my self I'd like to see some that you members find useful.
Backup is good (although I suspect most people use other software like BackupPC or Amanda to do it.)
I'm currently looking a way to ease my life with multiple Joomla updates.
Every time an update comes by I have to extract the zip file and do a copy to all folders under /var/www/domain1.com/web/ folder and then domain2 etc.
Also a script to backup databases to each domain's tmp folder would be a really great.
Anything really. Open stuff is so great because you can just take what you want and modify it to suit your needs.