if you'd like to write some applications (and perhaps an alert for mon) which implement rotating "on call" schedules, have a go at this code that i've written:
http://www.kernel.org/software/schedule-oncall/ there is a perl module called "Schedule::Oncall" in the schedule-oncall*.tar.gz file, which is used by the example applications found in the schedule-tools*.tar.gz file. the tools include a program which displays on-call schedules as ascii text or html, and another program which, when used as a mail filter, redirects the mail to the appropriate on-call person. i've not yet submitted the module into CPAN. have fun.
