I'm going to second dd on the Bailey Bay/Burke portage. It was the very first portage I ever did way back when, and I thought it was a damn long trek, carrying a couple of very heavy packs (single portaging back then). When we got through it and our experienced leader said it was the easiest portage we were going to have all week, I thought he was joking!  ;D  I learned much about portaging after that  :o  But it's still my favorite!

I think the most memorable portage for me is the swamp portage between Grey and that little unnamed lake on the way to Kash. You have the bog/swamp/marsh in the middle, and then the deceptive fork in the road that takes you back to Grey if you go the wrong way. Slipped off the logs my first time through there and sank up to my armpits in the muck  :P

Then again, there a lot that have special memories  ;)