Zinewiki is amazing. I already have promotion there. As well here are two other online places to advertise:

1) fanselfpub.wetpaint.com

While more a place to celebrate ALL types of self-published stuff, there's a section on zines (it's also easy to create a section for comics Yul!). I'm involved in science fiction zines... I'd love for others to cover the areas I don't know.

The Wetpaint system is very easy to pick up.

2) tiddlyspot.com/selfpubzine

Based on the Tiddly Wiki engine, this is a more focused wiki. You have to navigate to the areas to post.

NOTE: These are both more to promote zine series, not just individula zines.