I've been thinking about how to use SNMP to graph data like DHCP lease count in ROS. Then I thought it would be very useful if ROS could make an SNMP oid point to global script variable so that you could schedule a script to pull any value you want. Then you could retreve the value with SNMP.
DHCP lease count
BGP prefix count
BGP/VPN peer uptime
route hop count
Wireless client registration count
Custom script values for endless uses