One feature that I would occasionally find useful when trouble shooting my network would be to be able to force a specific device on the “Client List” display (Status → Client List) to have to renew it’s IP address & have it dropped from the Client List if it does not respond. I find the little icons on the left side of that list that are supposed indicate status just add clutter and are not very accurate as to whether the device is really active on the network. I’d also like that capability at the VLAN level (force everything on a specific VLAN to have to renew their IP addresses), as well as being able to specify some arbitrary LAN IP address range & force everything in that range to have to renew. The only way I know how to force a bunch of stuff to renew their IP addresses is to reboot the router (& often the devices connected to it), which in many cases I don’t want to do.
(RFC3203 describes the DHCP server FORCERENEW command. Don’t know how widely it’s implemented. http://www.ietf.org/rfc/rfc3203.txt)