DARK FORCES is a real tour-de-force to read. There are some incredibly imaginative stories in here. My personal favorites are "Where the Summer Ends" by Karl Edward Wagner, a story set in Knoxville, Tennessee that delivers a new and horrifying spin on an old "Japanese import"--namely, kudzu; and "Children of the Kingdom" by T.E.D. Klein, about an ancient race of half-human beings that creep stealthily through the sewers of New York City and that may have been responsible for the 1977 blackout in that city (well, not really!). Other good stories were "Dark Angel" by Edward Bryant, "Vengeance Is." by Theodore Sturgeon, "Lindsay and the Red City Blues" by Joe Haldeman (this story is very similar to "Dark Angel" in one respect but I won't spoil it for you--you'll have to read the story to see what I mean), and "The Night Before Christmas" by Robert Bloch (anything by Bloch is great!)
All in all, a must-read for the serious short horror fiction aficionado.