I'd like to see an Exiles/New Excalibur crossover. Two books written by Chris Claremont. Both off in their own little corners of the Marvel Universe. One team that hops from reality to reality fixing problems created by those pesky bugs. The other team had a recent time travel excursion, and is lead by a guy that's no stranger to alternate realities himself.
The trick is that I don't want it to be any big event, just a little meeting that leads to a good old fashioned misunderstanding battle, and an eventual team-up against something. The roadblock to the misunderstanding part is each team currently having one of the Braddock siblings, but maybe Captain Britain could get lost in Crosstime someplace, and that leads Excalibur (searching for him) into a run-in with the Exiles (possibly aware of his presence in other realities, which would almost certainly get Psylocke fired up to help him).
Claremont's already had Roma, a force for order I think, pop up in both books (albeit once in flashback). One could argue that the Exiles, with their missions to "save" realities, whether the inhabitants of the reality they're messing with want it or not, could be an unwitting instrument of Chaos, especially with Proteus on the team (even if he doesn't realize it yet), and Captain Britain probably represents Order, so there's a potential for some sparks there.
It's just something that might be fun to see, if given a proper build-up in the titles. Two teams that happen to converge on the same place at the same time, and go from there. Doesn't have to be part of something company wide, maybe more on the scale of the Avengers-Defenders War. Or maybe even the upcoming Justice League/Justice Society hoo-hah, though I bet that's going to cast significant ripples over the DCU.