I have no idea where the word
doujinshi originates from. I've tried to find its
origins many times but always
failed miserably.
The vast majority of doujinshi's I've come across are definitely yaoi orientated. Understandable really - why would one want non-yaoi doujinshi when they have the original manga?
I honestly can't explain to you the attraction of such things, even after being a fan for such a long period of time.
In the ever expanding world of manga and anime it has been my experience that manga fans either adore the original, or they adore the yaoi or yuri side to it. Rarely are people obessesed or infatuated with both. Doujinshi is an expansion of the yaoi and yuri fandom, pushing past the limitations of amature fanfiction into a totally different league. Why read about your favourite characters getting it on?
Let us see it damnit!
Doujinshi is, beyond reasonable doubt an infringement of copyright laws. Because of this, it is illegal in places such as Singapore... but of course, these restrictions don't serve to make it any less popular.
However, mangaka aren't stupid. They know full well that some of the interest generated in their manga creations is generated by the yaoi and doujinshi fandoms. As a result, the wise mangaka do not make any effort to crack down hard on such things. They really do do them a service, although I doubt they'd admit it publically (there are ethics to uphold here children).
It surprises me also that many of today's highly successful mangaka originally started out life as doujinshi artists, so of course they would have no complaints about the things - doujinshi is probably the only thing that helped them pay off student loans. A god send!
cos-plays, comic jams, other festivals which involve manga are likely places for doujinshi hunts. I have heard that they are very difficult to find in English but are plentiful in Japanese and Chinese (if you know where to look, of course). I can vouch for this - I haven't a single English doujinshi in my collection.
Doujinshi range greatly in style, with as almost broad a base as manga. They extend from sweet and sappy barely shonen ai, to hardcore lemon action (with a million different shades between). Some vaguly follow the grounds set by the manga, others go flying off into the dark abyss of original art.
Something for everyone? Well - no.
Something for any self-respecting-manga-or-anime-jrock-crazy-fan? Now you're talkin'.