Animethon 19 was this weekend. I wish I knew what a great convention this was before now- one year, maybe in 1998 or so I blundered into it and it was tiny. There were maybe a dozen people in a classroom watching an anime movie, my friend and I popped in to watch for a bit and then we left, and that seemed to be the extent of it. Turns out it's grown since then. I think I heard there were something like 7000 people there over the course of the weekend- not bad at all. I went on Friday thinking I would zip into the artist alley since I knew Drake Tsui would be there, and wound up making a weekend of it. Even brought the family out on Sunday.
One of the things that I think is really cool about it is it's been held at Grant Macewan College (University now) which is one of my favorite buildings ever. Crazy towers and spiral staircases and walkways and a big clock and stuff.  Great quad-type greenspace outside which provides great backdrops for cosplay photography.
Downside- they announced at the closing ceremony that there would be no Animethon 20 unless a whole lot of people stepped up to volunteer and share some of the load. More details here.