Alright, this is a thread for posting fanfics that you personally recommend due to quality. I'll start.
Lost in the Woods (Star Trek: The Next Generation/Firefly Crossover)
Tiberium Wars (Command & Conquer Non-Crossover)
Through A Temple (Star Trek: Deep Space Nine/Mass Effect Crossover)
Renegade (Command & Conquer/Mass Effect Crossover)
The Confederate (StarCraft/Warhammer 40,000 Crossover)
Finishing the Fight (Halo/Forgotten Realms Crossover)
Sleight of Hand (Star Trek: The Next Generation/Yu Yu Hakusho Crossover)
Aeon Entelechy Evangelion (CthulhuTech/F.E.A.R./Neon Genesis Evangelion/Revelation Space/Eclipse Phase Crossover) (WARNING: This fic is Grimdark. As in, "makes Drowtales look light and fluffy" grimdark. Not for everyone.)
Emerald Genesis (Green Lantern/Neon Genesis Evangelion Crossover)
Shinji Just Snaps And Totally Wails On Everything (Neon Genesis Evangelion Non-Crossover/Comedy)
The Enterprise Strikes Back (Star Trek: Enterprise/Star Wars Crossover)
A Hero (Doctor Who/Puella Magi Madoka Magica Crossover)
Now, what fics do you recommend?