Okay, here goes: the plot for the ultimate fanfic novel...
The Enterprise (NCC-1701) encounters the Enterprise (NCC-1701-D) after going through a rip in the space/time continuum; Kirk and Picard team up to do battle with the Galactic Empire, during which they enlist the help of Luke Skywalker and Obi-Wan Kenobi. In doing so, they go back in time to Earth, where they beam down to the Seaview and meet Admiral Nelson and Captain Crane. By then, Nelson and Crane have drafted Harry Potter, who has begun dating Buffy; both have also become U.N.C.L.E. agents. The whole bunch of them go off into space again, where they find the Jupiter 2. Kirk boinks Maureen Robinson and Harry leaves Buffy to begin a doomed affair with Penny; in the meantime, the Robot downloads Max Headroom and learns how to drive K.I.T.T. Spock discovers how to communicate with Ripley, who tells them how to find the Predator. But the Predator is busy fighting the Master Chief on Halo, so the whole crew proceeds to the Death Star, in the meantime picking up the two guys from the Time Tunnel (can't remember their names, sorry), who've landed on the Enterprise (NCC-1701, not NCC-1701-D ... that would be too much of stretch) by mistake. But when everyone finally gets to the Death Star, they find that Darth Vader has struck an accord with the Shadows, who in turn have brought along Londo Mollari, who in turn has become friends with Dr. Doom. This means, of course, that the Fantastic Four aren't far away, with the X-Men not far behind. But because the Thing knows Doc Savage, and Doc knows the Shadow (as opposed to the Shadows, natch), and the Shadow is friends with the Avenger ... well, of course, they get in on the act, too. But then there's another rip in the space/time continuum, and everyone is transported to Oz, where Harry finds his true love in Dorothy, the Tin Man has a lighter-saber duel with Darth Vader, and the Cowardly Lion has an interesting but hopeless affair with Judy Robinson. Finally, the Wicked Witch of the West sends her flying monkeys, led by Luke Skywalker, on a blitzkrieg attack against the Death Star, while the Seaview goes back to Earth to find the Seaquest; the two subs do battle, but the conflict goes unresolved before yet another space/time whatever opens up and they're transported to the Land of the Giants, where the surfer dude from the Seaview meets the hot stewardess who's always running and screaming (you know who I mean). Oh, and I almost forgot: Buffy deflowers Will Robinson, who is grateful.
There's more, but you'll have to pay me $50 thousand for the idea before I tell you the rest.
If you liked it, go buy one of Allen's books.