Fantasy Crossovers/Teamups?

Seeing Big Barda in Birds of Prey, teaming up with possibly my other two favorite heroines in the DCU, got me thinking about all the crossover/teamup stories that I'd really like to see.

For example, I'd always wanted to see what would happen with a team-up between Nightwing and Sand.

In the Golden Age, both characters played strikingly similar roles. Non-powered sidekicks of non-powered heroes, optimistically named cheerful compatriots to dour detective types (in admittedly goofy costumes)... Sure Sandy tended to be a bit more cerebral, and Robin more physical, but their roles had a lot of striking similarity.

Of course, sixty some odd years later, the characters are taken into vastly different directions. Robin was never a compatriot of Sandy, instead being born and growing up decades later. Sandy in the meantime fell by the wayside, only to be revived and revamped into a sandmonster.

But what I find particularly interesting is that at this point in time, both characters are once again the same age (thanks to many reboots and nifty anesthetic chambers) and in oddly similar circumstances as sidekicks trying past their mentors' legacies.

I just think seeing a team-up would be really really neat!

I'd also really like to see a Kara Zor-El, Jason Todd meeting, if not a team-up, if only because as the black sheep (of sorts) in their respective "families", I think there'd be some interesting interaction.

And I'd always wondered what would have happened if Hawkwoman and Hawkgirl had actual time to interact with each other.

And I *still* want to see what happens when Phyla Vell meets her little (big?) brother!

What about you guys? What crossovers/team-ups would you really like to see?