Once upon a time anyone that could afford access to a press could publish. Now anyone that has a printer, scanner and computer can do it.
Zines are independantly produced minature "magazines" sometimes more like pamphlets, sometimes pretty well done mags. They come in E-zines, Fan-Zine and printed Zines.
Often the issues discussed in them are political, or politically incorrect and will not be published in a regular magazine. Other times there just for a very small target group or in the name of artistic expression. You name the topic and there's a Zine out for it somewhere. A few magazines (adbusters I believe is one) started as zines and became very popular.
The one I'm working on currently would be a monthly, varied in topic (we have almost a years worth of concepts plotted out but more ideas are always welcome if anyone wants to share) with as much thought and work put into design, layout and overall visual appeal (all parties involved are artists in one form or another) as the articles themselves.
Zines can usually be found in the artsy activist hangouts, on university and campus grounds and in the occasional store. My hope is that "Guide" will be sold out of stores (starting small of course).