There are many autobiographical online comics out there, some are as far as we know, are 100% autobiographical, like goraina 's Smile, or 99% like American Elf, which just changes the way the people look.
But then, there are those are a little less autobiographical, like the Devil's Panties which is sometimes what happened and sometimes what the author WANTED to happen, and then there are other's like Candi, mix real life with fiction.
But this isn't where it ends, as you get to know the author of some comics, you notice how the author's life leaks into their comic in some way or another.
There are MANY many webcomics which simply have themselves in their comic, and even if what all that happens in the comic is fiction, it's still the author in there, and you get to know the person through the comic, when that characters speaks, we know it's what the author thinks. Almost every gamer comic falls into this category.
And then we have the ones that are only a little autobiographic, the ones that take place in the same city as the author. Wapsi Square is a good example, some places are real and you can tell some things that happened there have been experienced by the author.
I always find it amusing how the whole perspective on some comics change when you get to know them.