Shutdown/Suspend on low battery

[Julien Poissonnier]

Hi,
is there a way to to shutdown or suspend (or execute a command) when the 
battery is low, for example when it reaches 5%.
Are there any ACPI-events when the battery discharges ? Or would I need 
some daemon that constantly checks the remaining battery capacity ?
How about shutting down (or suspending, if I get it to work...) after a 
certain amount of idle time ?