Girl genius and Slayers do have a lot of things in common. Mainly the whole humor/fantasy story style. I also see a lot of similarities between the Other and Mazoku.

Lina was originally going to be a mecanic. According to an interview with Hajime Kananza, the original story had Luna as the star, and Lina was a younger, cloned version of Luna who loved mecanincs. So really, it just demanded to be done!

Victorian zel n' Gourry coming soon (and dare I say...hot.)