Wake on LAN in the enterprise

Hello... I'm trying to get a handle on implementation of wake-on-lan in an enterprise environment. Cisco gear, lots of subnets. I've made it work with directed broadcasts, but I'd really rather not have 40 or 50 'ip helper-address x.x.x.bcastaddr' statements on the vlans with the SMS servers. Are there any enterprises that are doing this for large (100+) numbers of subnets? I can't find a single example anywhere with more than 2 networks. I've searched the Cisco-NSP archives as well with no luck, but maybe I didn't go back far enough. Thanks for any help you can provide. Berry Mobley