I suffer from migraines as well.
A few years ago, I had 1/2 a joint left over from a party a few nights before - don't know what strain. I got socked with a bad migraine and had heard that pot could help.
I took one hit from it and like a veil lifting, everything just went away - pain, nausea, etc.... all gone. I sat around for a few minutes waiting for it to rebound, but it never did.
Since then, I've never had quite as dramatic effect - I'm sure it's strain dependant. However, almost any pot I've had around has definately made an improvement.
Typically it at least helps the nausea enough that I'm able to swallow pain pills and actually keep them down.
Sure has made me a believer in pot's medicinal qualities
Sure would like to know what that first one was though....
I have noticed that since I've been smoking more "regularly", I rarely get migraines at all anymore