D.H.
Family eGuide (familyeguide.com) is my favourite by far! They are a guide for Flower Mound, Lewisville, and Highland Village (although they also include many activities in the surrounding areas) - it is very well organized and super informative. My family and I try to pick at least one or two activities from Family eGuide each week.
I also look at gocitykids.com and find a lot of other DFW metroplex activities there.
D.