If you're reading this blog, you probably already know this, but Ackerman was the quintessential, original "fanboy", in 1958 founding the legendary magazine Famous Monsters of Filmland that ran for nearly a quarter century and literally gave birth to the modern phenomenon of horror/sci-fi/fantasy fandom as we know it. In fact, it was Forry who coined the term "sci-fi" in his early issues of FMOF. He inspired generations of "monster kids" in the '50s, '60s, '70s and '80s, and his influence continues to be felt.
Additionally, Ackerman had gathered together over his almost century of life the single most impressive collection of genre memorabilia on the planet. He enjoyed the friendship of everyone from H.P. Lovecraft to Harry Knowles. The man was literally a pop culture phenom all too himself, and the world is poorer for his passing.
For a truly amazing tribute, I direct you to Knowles' Ain't It Cool News, where you can check out tributes from Phil Tippett, Rick Baker and Paul Dini, as well as a moving final farewell written by Ackerman for Knowles five years ago, in anticipation of his death.
Most of Ackerman's heyday occurred before my time, but even though I grew up more in the era of Starlog/Fangoria, his was a name I always knew and respected--the godfather and president emeritus of the entire fan community.
R.I.P. Uncle Forry.