Two others of those are pretty decent, 'thou they haven't been updated recently. And a couple more of them I'm on the fence about due to not enough content yet.
Startrek/BtVS/SG Crossover
http://www.tthfanfic.org/Story-28697/HM ... ty+Box.htm
Willow and Xander dress as their Star-trek RPG characters in honor of Jesse's memory, while Buffy decides a comm-badge would be pretty. Meanwhile on the Stargate side of things Apophis is on his way and Daniel has just got back from the Quantum Mirror.
nBSG/SG/BtVS Crossover **Warning! as of the end of current writing Xander is largely replaced by his costume persona of Karl Agathon**
http://www.tthfanfic.org/Story-28765/Ab ... Lovers.htm
This is the only ship of the line fic I know that pulls one of the crossed characters wholesale into the Sunnydale universe. Best parts of this are the Stargate side misunderstanding of the situation.
Startrek/BtVS/SG Crossover
http://www.tthfanfic.org/Story-28697/HM ... ty+Box.htm
Willow and Xander dress as their Star-trek RPG characters in honor of Jesse's memory, while Buffy decides a comm-badge would be pretty. Meanwhile on the Stargate side of things Apophis is on his way and Daniel has just got back from the Quantum Mirror.
nBSG/SG/BtVS Crossover **Warning! as of the end of current writing Xander is largely replaced by his costume persona of Karl Agathon**
http://www.tthfanfic.org/Story-28765/Ab ... Lovers.htm
This is the only ship of the line fic I know that pulls one of the crossed characters wholesale into the Sunnydale universe. Best parts of this are the Stargate side misunderstanding of the situation.