I'm responding to this thread mainly to revive it again, since it was started 3 years ago. I'm fascinated to hear now what people think, since it's been 3 years and ebook publishing has really taken off in those 3 years. My guess is that the list of what genres are successful in epublishing is going to look both similar and different.
I've been doing more searching for self-published books vs. traditionally published books on Amazon when I chose my reading material (trying to focus on SP books, since that's the route I want to go and I'm trying to support the concept in general). Someone here mentioned that women's fiction doesn't seem to be a big seller in the SP world. Since this is one of the genres I'm interested in, I've focused on a lot on that and I am finding now that there are many options and many top sellers. Women's fiction is quite broad, but many of the books I see fall into this category as well as others. So maybe this is something that's changed in the last 3 years.
Also, I think it's important to keep in mind that many mailing lists geared towards offering low cost/no cost ebooks each day have come onto the scene and they allow readers to filter by genre before they subscribe. Consequently, readers can get a daily list of deals and top sellers in their niche genres. So, for example, many of the books in women's fiction that I see come from those lists and I see usually that the are about 1-2 on the daily list. That's still not a lot, compared to books on the list from other genres (for example, I also have Mystery and Suspense and Thriller on the list and I usually see around 2-3 books from each of those genres on the list daily), but it definitely means to me that it's a genre that many readers want to see.
Djuna