Ooo!! I know I know! Pick me pick me!! *jumps up and down*
Naoko Takeuchi created Love Witch after Sailor Moon!! ^__^ Behold my geekdom.
I was so happy when they put in Akira, Nokoru-sama, and Suoh in the 4th Tsubasa manga!! Even if they're there for like, three pages... I squealed and jumpe dup and down when I saw them (they're too cute not to love!!) I can't wait to see them animated on TC; I never got to see the CSD anime, aside from screencaps...
I saw the first tape of that (yes, TAPE...this was back in the ancient times.) It's a fun little show. Now, when they show up in Tsubasa, are they their kid selves from CSD, or the adult versions from X?
Oh, and I ended up answering my own question about other crossovers when I went to watch a fansub of Detective Conan. ^^;; Before Gosho Aoyama did Conan, he did a manga called Magic Thief, which was about a high school student who moonlights as a jewel thief called Kaitou Kid, who uses all sorts of magic tricks to pull off his robberies. The series didn't do too well and was canceled after only two volumes. But apprentally Aoyama had a soft spot for Kaitou, because now he's a recurring villain on Detective Conan. Apprentally, later in the series he plays a major role and becomes Conan's archenemy-not because he's dangerous (he prides himself on stealing nonviolently) but because he's the only criminal who's as smart as Conan-and the only one he's never caught.
Also, he looks like Tuxedo mask, but with a monocle. Monocles are goofy.