I haven't been to any of these, but I've heard about it. I never was the kind to go to this type of thing where you meet up with people based on web community. To tell you the truth, I haven't really dwelled long enough with these specific communities to come have coffee/tea with them at the specific nights. But if you are bored, and want to make friends, but are too much of a computer nerd to so social things like go to bars, or some sort of salsa class, the internet meetups could be fun.

Calgary TNG: ca.groups.yahoo.com/group/calgary_tng/
This is an age exclusive meet up. 18-30 kinky folk come and hang out. They meet in low-key, quiet public places, like The Unicorn Pub.

Vampire Freaks: vampirefreaks.com/cult/calgary
VampireFreaks is a website that is much like Nexopia and Myspace. The Calgary Cult meets up every once in a while, and they have a nice forum to meet people and talk about gothic stuff in Calgary, like where's the best place to buy hair dye?

And then there's meetup.com. Here's a list of meetups from there for Calgary that might interest you... Of course there are tons of other groups you may like, go a browse there:
Witches: witches.meetup.com/1322/
Body Modification:bodymod.meetup.com/73/
Murder Mystery Party: murdermyst.meetup.com/7/
Fight Big Media: fightbigmedia.meetup.com/261/
Adbusters and Culture Jammers: adbusters.meetup.com/16/
Anime: anime.meetup.com/494/
Satanism: satanism.meetup.com/cities/c.../calgary/
Druids: druid.meetup.com/93/
Live Action Role Playing: larp.meetup.com/135/
Vampire: The Masquerade: masquerade.meetup.com/cities/...calgary/

And there's tons more!

I didn't realize I could come up with such a big list from meetup.com

Anyways, go have fun then haha