Some good things, but I have to say that Jedi Harris, when I last saw it, is a classic Xander Stue story.
I've can and have break down the implausibility of the entire scenario of Xander getting powers perminately from the Halloween incident. Skills, yes. Powers, no.
Anyway, here's some good stories I've found:
Transformers/Godzilla: Timetrap -- Heisie Godzilla, Transformers Cartoon (G1?) and Beast Wars. Optimus pwning Hotrod, Transmetal2(!) Gigan, and it can take place in full continuity of both!
Urban Legends -- Gargoyles/Godzilla: The Series. Incorporates some of the "Expanded Universe" fans have set up as well as some other fanon elements that annoy me to no end, but it is still awesome.
Runaway Trains at 3 a.m. -- a Smallville/Buffy crossover that doesn't suck. Dawn and Clark have both runaway and meet each other at a trainstation. The banter between these two characters is well done.
An Angel -- Angel is shot taken to County Hospital for treatment. Pronounced DOA and sent to the Morgue. Cordy has to break in and get him some clothes/get him out. Yes, it's a Angel/ER crossover without "BIG REVELATIONS!"
The Scarer and the Slayer's Sis -- Buffy/Monster's Inc. It workes so well it's frightening. Short and sweet to boot. What are you doing? GO READ IT!
Original Sins -- Gargoyles (Timedancers subset)/Tenchi Muyo! Set in the past, involves Spacespawn and Old Man Masaki.
The Scarab THE best Buffy/SG-1 crossover. Period. "Bridges" is a close second, but this one actually feels like a well written episode of BOTH series.
Diary of a Mounty LXG: 1936 -- actually remembers to draw from Literary sources for the crossover. Though it is one hell of an odd team that's assembled.
Oddly Familiar -- Xander Dresses up as Batman for Halloween. This isn't about the night, though, it's about what Bruce remembers AFTERWARDs and how Xander's personality/outlook alters HIM. This is the best of the "Xander dresses as someone else" simply because it's not about giving Xander powers that he doens't need!
Operation: Retrieval -- Buffy/Alias. Simply story. Buffy has a Rambaldi artifact, Sydney needs to get it. She can't get past their defences, so she calls in some backup--and get's Riley's squad. He settles the matter in the most obvious way possible. (Rambaldi objects don't sell for much on E-bay, apparently). Good humor.
An Investigation into the Murder of Nikki Wood - "A Law and Order BTVS Crossover.NYC Homicide Detective Lennie Briscoe tells his partner a story about one of his first cases.A story about a murdered woman found in a subway car."
Evil thou be My Good -- HP/Hellraiser crossover. Dark, gory, and Pinhead in the HP Universe. The sheer oditiy of the combination is enough for the recomendation!
The BSC, Vampire Slayers -- Hillariously well written parody, Buffy crossed with Baby Siter's Club. I can't make that kind of Crack up!
Hellblazer: Hogwarts -- John Constantine sucked into Harry Potter's world. He proceeds to behave like John Constantine and piss people off. Incomplete, but awesome nonetheless. When he first see's Harry, he says "Tim?"
Connections -- JLU/Teen Titans, but written with the audience of the Comics in mind. "During a routine mission Jinx reappears briefly, and Flash is determined to find her alone. Unfortunately for him, Shayera's determined to help." Great Flash voice, if a little to "dark" for the media chosen.
The Burning Fairy Luna Lovegood discovers the Cthulhu Mythos...and doens't make it back!
CSI: Death By Chocolate -- CSI/Charlie and the Chocolate Factory (Modern Encarnation). It's so odd, and it works!
More later, that should hold a lot of attention...