He's referring to crossover episodes between those shows. There was a Charlie's Angels episode set on the ship from The Love Boat, and there was a mutual crossover between TLB and Fantasy Island. And Detective Munch from Law and Order: SVU (who was originally in Homicide: Life on the Streets) once appeared in an episode of The Lone Gunmen, a spinoff of The X-Files.
Actually, it was an episode of The X-Files
featuring the origin of the Lone Gunmen (it aired a few years before they got their spin-off).
And just to chime in on the NF discussion, I'm a long-time PAD fan and I love the unique voice he brings to the Trek universe.
And slightly more on-topic, I'm also a Titan and James Swallow fan, and am looking forward to Synthesis
. Which I've yet to have a chance to read.