Hi. New here. Not new to crossovers.
Newest ones are at the bottom, since I went backwards when compiling this. Everything's on ff'net, because I am lazy as hell about updating my own site.
The Chosen Few: Ali McKenzie's Shadowlands. Cable and the X-Men/Buffy: the Vampire Slayer PG13 (language, violence)
http://www.fanfiction.net/s/59177/1/AliMc's Shadowlands were a concept that came about shortly after the 12 Saga storyline. Basically, what if something went wrong, and all realities began falling into each other and shifting across each other...? There is a massive, lovely Shadowlands archive out there.
http://www.comicfic.net/shadowlands/ (some are crossovers, most are not--check out anything by Ali herself, Lise, or Persephone Kore)
Brief Moments of Lucidity - X-Men/Buffy PG13 (language)
http://www.fanfiction.net/s/476239/1/Kitty Pryde and Willow Rosenberg meet at a convention in Atlanta...
The Paninaro of Angry Weasels Named Flibble - X-Men/Buffy/Touching Evil/Second Sight R (violence, language)
http://www.fanfiction.net/s/887786/1/When Pete Wisdom (and a friend or two) swipe something from the British museum, Rupert Giles is dragged into a world of mayhem... (features characters borrowed from UK Touching Evil and Second Sight)
Violence or Revenge - Buffy/X-Men R (violence, language)
http://www.fanfiction.net/s/887805/1/Strange piece, all-dialogue. Drusilla recruits some help against Buffy and Co...
Melted Ties - Buffy/Red Dwarf PG
http://www.fanfiction.net/s/1047784/1/ Erm, why didn't Glory kill Dawn, like she threatened to? (and how does a mining ship lost 3 million years into the future come into it all?)
Tainted Photographs - X-Men/Farscape PG13 (language, violence, strange permutations of the spacetime continuum)
http://www.fanfiction.net/s/1280178/1/When Rachel Summers falls into Mojoworld again, she quickly figures out that something is wrong. But will GameSprite!John be able to help?
Intermingled Colours - X-Men/Farscape R (sex, femslash)
http://www.fanfiction.net/s/1463039/1/Ororo Munroe has always been fond of women... Chiana/Storm
It Was Summer - Blake's 7/Farscape PG
http://www.fanfiction.net/s/1687089/1/A missing scene from 'Rescue'; someone arrives to ease the dying of the light.
The Ring, the Wormhole, and the Leviathan - Farscape/LotR PG13 (violence, language)
http://www.fanfiction.net/s/1753550/1/When a certain ring falls onto Moya, the crew must decide what to do with it. A trip to Middle Earth doesn't help matters...
Hanging Around - Stargate: SG-1/X-Men: the Movie PG
http://www.fanfiction.net/s/1916813/1/Sam Carter shares a conversation in a park with Scott Summers.
Burning the Negatives - Stargate: SG-1/X-Men comics R (language, sex, etc)
http://www.fanfiction.net/s/1938430/1/What if the wrong Pete was dating Sam Carter, and what if there were... nefarious reasons involved? As a warning, I... am disturbed by this fic. It's not evil. It's just... silly. (highly Sam/Jack shippy, despite Pete)
Found Wanting - Stargate: SG-1/Farscape R (sex)
http://www.fanfiction.net/s/1964195/1/Two slightly lost souls find something that could be solace...
Walking Cliche - Ghostbusters (movie, although the comicbook inspired this)/Stargate: SG-1 PG
http://www.fanfiction.net/s/1983177/1/C'mon, I can NOT have been the only one who thought of this during 'Lockdown'...
Lost in Space: A Cliche in Five Parts - Stargate: SG-1/Farscape R/PG13 (violence, language, etc)
http://www.fanfiction.net/s/2078712/1/Stargate: SG-1 meets Farscape. The Uncharted Territories may never be the same again. It all started one sleepy afternoon on Moya.... where I retcon Bad Timing and Affinity and ignore many things. (bits were written by A.j.)