Other than working on Star Princess, Yuki Shiro, Anime Detour, and my 5D's Christmas Special, I am throwing around some ideas for ONESHOT fanfictions, here are a couple of them:

1. The Witch's Embrace
Yugioh 5D's and Witchblade (The Anime) Crossover. Features Mina (Mikage) x Jack.
Mikage becomes the unlikely new host of a magical weapon known as the witchblade. When Sayer (Divine) finds out about it, he wishes to seize it from her to place it on his prized warrior: Aki Izayoi. The plot may be somewhat incomplete however, since it is meant to be experimental.

2. An original character for a possible oneshot:

Johnny Hino Atlas
Age 3/Male
Short Blonde Hair/Violet Eyes
Wears a pair of denim shorts and a white T-shirt.

Johnny is the son of Jack Atlas by a mute girl named Aoi Hino. Unlike her son, she has long black hair and her eyes are blue. She had been Jack Atlas's girlfriend when Team Satisfaction was around. But the two of them went seperate ways after the team broke up, as her older sister, Aka considered him too dangerous to be around. She found she was pregnant with Johnny and he was born just before Jack left the Satellite. But he never knew that he had a son.
Aoi and Aka were absorbed in the black fog the Dark Signers caused, but Johnny somehow managed to escape. Takaya found him and he is now in Martha's care.
He is a very sweet and gentle boy, but he's shy like his mother.

The story would basically be when Jack and the other signers come to Martha's and he happens to meet Johnny.

Disclaimer: I DON'T like Jack Atlas. To me, he will forever be the jerk who took Yusei's bike. But I wouldn't be suprised if he did get some girl preggers. I would hope his offspring would be nicer than him.