I'd like to use a linux pc purely to collect rss feeds, but would like to minimise it's power usage as much as possible.
Presumably I would create some kind of cron job to bring it in and out of sleep mode or are there better ways of tackling this?
Set wake up alarm in RTC, then put the computer in standby or suspend(-to-RAM) mode. Some motherboards support waking up from hibernation (suspend-to-disk), but I guess that'll be too slow.
echo `date '+%s' -d '+ 5 minutes'` > /sys/class/rtc/rtc0/wakealarm
echo -n "mem" > /sys/power/state
Replace "mem" with "standby" for stand-by instead of suspend.
BTW. MythTV's wiki has got some more in-depth info end examples. http://www.mythtv.org/wiki/ACPI_Wakeup