http://omnireboot.com/
found via http://urbanhonking.com/spacecanon/2013/08/12/introducing-omni-reboot/ (a great place to visit for fans of golden-age scifi, including some interview excerpts with like-minded folks)
I WISH they would release their back-catalog online.
I had every OMNI magazine from 1986 to 1992 or so and there was fiction in there that was never reprinted elsewhere... and I tossed them all out 15 years ago (yarg!)