This list of crossover pairings/scenarios was compiled from the unfulfilled requests sent in by participants in the ficathon. (And a couple I chucked in for fun, to bring it up to an even one hundred.) The slashes and ampersands (that's the & symbol, indicative here of a relationship that's not romantic/sexual) are only suggestions. If a scenario with a / turns out to be ampersand or a scenario with a & turns into slash or het, no problem. Send it in anyway. There are no minimum length requirements, ratings restrictions or time limits on these either.
Also, participants in the original ficathon should feel free to write requests they originally submitted.
1. Bialar Crais (Farscape)/Alfred Bester (Babylon 5)
2. Mal Reynolds (Firefly)/Kathryn Janeway (Star Trek: Voyager)
3. River Tam (Firefly) & The Heart of Gold (Hitchhiker's Guide to the Galaxy)
4. Mele-On Grayza (Farscape)/Servalan (Blake's 7)
5. Simon Tam (Firefly)/River Tam (Firefly)/Lennier (Bablyon 5)
6. Kosh (Babylon 5) & Q (Star Trek)
7. Arthur Dent (Hitchhiker's Guide to the Galaxy)/Dave Lister (Red Dwarf)
8. Kaylee (Firefly)/Teal'c (Stargate SG-1)
9. Vir Cotto (Babylon 5) & Star Trek: Deep Space 9, Bajoran Occupation time frame.
10. Starbuck (New Battlestar Gallactica)/Aeryn Sun (Farscape)
11. Susan Ivanova (Babylon 5)/Chekov (Star Trek TOS)
12. Roj Blake (Blake's 7) & Farscape
13. Mal Reynolds (Firefly)/Han Solo (Star Wars)
14. Scorpius (Farscape)/Lyta Alexander (Babylon 5)
15. Jake Sisko (Star Trek: Deep Space 9) & Firefly
16. Padme Amidala (Star Wars)/Zev (Lexx)
17. Tyr Anasazi (Andromeda)/Seven of Nine (Star Trek: Voyager)
18. Jean-Luc Picard (Star Trek: The Next Generation) & Babylon 5
19. Jack O'Neill (Stargate SG-1)/Daniel Jackson (Stargate SG-1)/Julian Bashir (Star Trek: Deep Space 9)
20. Scorpius (Farscape)/River Tam (Firefly)
21. Zoe (Firefly) & Hitchhiker's Guide to the Galaxy
22. Chiana (Farscape)/T'Pol (Star Trek: Enterprise)
23. Leia Organa (Star Wars)/Teal'c (Stargate SG-1)
24. Aeryn Sun (Farscape) & Space: Above and Beyond
25. Ford Prefect (Hitchhiker's Guide to the Galaxy)/Nerri (Farscape)
26. Odo (Star Trek: Deep Space 9)/Cally (Blake's 7)
27. Obi-Wan Kenobi (Star Wars) & Scorpius (Farscape)
28. Kaylee (Firefly)/Sam Carter (Stargate SG-1)
29. Jack O'Neill (Stargate SG-1)/Kira Nerys (Star Trek: Deep Space 9)
30. The 4th Doctor (Doctor Who) & Star Wars
31. Bialar Crais (Farscape)/Travis (Blake's 7)
32. Dureena Nafeel (Crusade)/James T. Kirk (Star Trek TOS)
33. Star Wars & Hitchhiker's Guide to the Galaxy
34. Delenn (Babylon 5)/Inara (Firefly)
35. Daniel Jackson (Stargate SG-1)/Rommie (Andromeda)
36. The Doctor (Doctor Who) & Stargate SG-1
37. Qui-Gon Jinn (Star Wars)/Jacob Carter (Stargate SG-1)
38. John Crichton (Farscape)/Original Ripley (Alien). Double points for both Johns.
39. Kerr Avon (Blake's 7)/Data (Star Trek: The Next Generation)
40. Servalan (Blake's 7)/Saffron (Firefly)
41. Trip Tucker (Star Trek: Enterprise)/Kaylee (Firefly)
42. Marvin the Paranoid Android (Hitchhiker's Guide to the Galaxy) & Paranoia (Red Dwarf)
43. Daniel Jackson (Stargate SG-1)/John Crichton (Farscape)
44. Simon Tam (Firefly)/Chiana (Farscape)
46. Data (Star Trek: The Next Generation) & C3PO (Star Wars)
47. Julian Bashir (Star Trek: Deep Space 9)/Mal Reynolds (Firefly)
48. Han Solo (Star Wars)/Susan Ivanova (Babylon 5)
49. Jean-Luc Picard (Star Trek: The Next Generation) & Blake's 7
50. Dylan Hunt (Andromeda)/Janeway (Star Trek: Voyager)/Sherridan (Babylon 5)/Aeryn (Farscape)/Mal (Firefly)/Janet (Stargate SG-1)/Luke (Star Wars)/Ripley (Alien)
51. Kosh (Babylon 5)/Thor (Stargate SG-1)
52. Daniel Jackson (Stargate SG-1)/Saffron (Firefly)
53. James T. Kirk (Star Trek TOS) & Alfred Bester (Babylon 5)
54. Seven of Nine (Star Trek: Voyager)/Starbuck (New Battlestar Gallactica)
55. Aeryn Sun (Farscape)/Jack O'Neill (Stargate SG-1)
56. Trance (Andromeda) & Babylon 5
57. General Martok (Star Trek: Deep Space 9)/Bra'tac (Stargate SG-1)
58. Jean-Luc Picard (Star Trek: The Next Generation)/Catherine Sakai (Babylon 5)
59. Q (Star Trek) & Lorien (Babylon 5)
60. Susan Ivanova (Babylon 5)/Sikozu (Farscape)/Sam Carter (Stargate SG-1)
61. Bekka Valentine (Andromeda)/Mal Reynolds (Firefly)
62. Scorpius (Farscape) & Spock (Star Trek TOS)
63. Alastair Gordon Lethbridge Stewart (Dr. Who)/Scotty (Star Trek TOS)
64. Kathryn Janeway (Star Trek: Voyager)/Jack O'Neill (Stargate SG-1)
65. Londo Mollari (Babylon 5) & Star Trek: Deep Space 9
66. Rommie (Andromeda)/Padme Amidala (Star Wars)
67. Leia Organa (Star Wars)/Dave Lister (Red Dwarf)
68. Jake Sisko (Star Trek: Deep Space 9) & G'Kar (Babylon 5)
69. Daniel Jackson (Stargate SG-1)/Mal Reynolds (Firefly)
70. Teal'c (Stargate SG-1)/Kira Nerys (Star Trek: Deep Space 9)
71. John Crichton (Farscape) & Battlestar Galactica
72. Leela (Dr. Who)/Cally (Blake's 7)
73. Starbuck (New Battlestar Gallactica)/Jayne (Firefly)
74. Yoda (Star Wars) & Vir Cotto (Babylon 5)
75. Ford Prefect (Hitchhiker's Guide to the Galaxy)/Daniel Jackson (Stargate SG-1)
76. G'Kar (Babylon 5)/Kira Nerys (Star Trek: Deep Space 9)
77. Kryten (Red Dwarf) & The Doctor (Star Trek: Voyager)
78. Sam Carter (Stargate SG-1)/B'Elanna Torres (Star Trek: Voyager)
79. Jayne (Firefly)/Kaylee (Firefly)/Han Solo (Star Wars)
80. D'Argo (Farscape) & G'Kar (Babylon 5)
81. Grey Council (B5)/Jedi Council (Star Wars)
82. Kira Nerys (Star Trek: Deep Space 9)/Kerr Avon (Blake's 7)
83. Andromeda & Stargate SG-1
84. Zoe (Firefly)/Aeryn Sun (Farscape)/Seven of Nine (Star Trek: Voyager)
85. The Doctor (Dr. Who)/Sam Carter (Stargate SG-1)
86. Scorpius (Farscape) & Garak (Star Trek: Deep Space 9)
87. D'Argo (Farscape)/Teal'c (Stargate SG-1)
88. Chiana (Farscape)/Jayne (Firefly)
89. Psi Corps (Babylon 5) & Peacekeeper High Command (Farscape)
90. Inara (Firefly)/Leia Organa (Star Wars)
91. Cally (Blake's 7)/Daniel Jackson (Stargate SG-1)
92. Arthur Dent (Hitchhiker's Guide to the Galaxy) & John Crichton (Farscape)
93. Quark (Star Trek: Deep Space 9)/Sam Carter (Stargate SG-1)
94. Thor (Stargate SG-1)/Q (Star Trek)
95. Shane Vansen (Space: Above And Beyond)/Jack O'Neill (Stargate SG-1)
96. Luke Skywalker (Star Wars) & Data (Star Trek: The Next Generation)
97. River Tam (Firefly)/T'Pol (Star Trek: Enterprise)
98. Deanna Troi (Star Trek: The Next Generation)/Jonas Quinn (Stargate SG-1)
99. Sikozu (Farscape) & Dr. Who
100. Arnold Rimmer (Red Dwarf)/Miklo Braca (Farscape)