To what end should interfaith dialogue serve?

Understanding.

I can talk to a person of the christian faith as an atheist and we can both come out knowing that one another isn't evil because they don't share our ideas. He can understand that I'm not trying to subvert is faith, and I can understand that he isn't trying to impose his will on me.

We can't really hope, and we probably shouldn't want, to change others faith. We can present to them what we see as correct, understand what they see, and see what path is taken from then on.

Tolerance is definately the key.

And common ground? Should interfaith dialogue seek to find common ground?

I belive that through understanding, the commen ground that many different faiths share would become apparent.

I'm not so sure common ground should be the end result of inter-religious dialogue. I feel that while many religions have a great deal in common, recognition of those commonalities, while helpful, shouldn't be the be all and end all.

I'd think a recognition of common goals and working towards them. Almost all major religions preach about a working for people who are oppressed and working to end oppression. I find that to be a much better "end" for inter religions dialogue.

Understanding yes, common ground yes, sharing personal faith yes, tolerance not quite.
I would hesitate to ever say tolerance, simply because some things aren't tolerable even when fully understood.

The difference here is "should" verses "does".
"To what end does interfaith dialogue strive?"
It's used to explain, convert, change opinions, or to use for self-reassurance in one's own faith.

To the idea of tolerance, it becomes an issue of passive acceptance.
Should that be the goal? Not necessarily.
To tolerate what, and how far does that go?

Some things shouldn't be tolerated, but they can be understood.
Simply because someone has a religious reason to do something, doesn't mean it should be tolerated.