If someone with an awesome superhero comic came along and offered a crossover opportunity, I'd love to jump at something like that. However, I really need to get my own universe well-established first, which could take some time. What I would really love to do someday is release a 2 part issue that's a standalone story, where either my characters enter their comic's setting or vice versa, and battle against or with the characters from their universe. Still, this is thinking very far ahead.