I have great luck with using my "second" runnings from big beers to make milds - I'll often cap the initial grains with some additional crystal or chocolate etc, if the original beer was pale, or if I feel like I need some extra flavor - but the roastiness of a dark beer really shines through in a mild. Normally I get a really drinkable and flavorful 3% beer in the end. I also keep some DME on hand just in case I want to bump the gravity a bit.
Vernacular - Used to spend lots of time in Batavia on business. I still miss the little Irish pub down town - especially the Summer Tuesday's BBQ!