One of my greatest pleasure is to stroll in the bookstore and discovering books - sometimes by their cover, other times by their spines. In any case, I pick up a book, briefly read its synopsis, and if it interests me, I will read the first page. If the first page intrigues me, and I have spare cash, I will buy it on the spot. Sometimes, if I feel like it, I will stop right at a cafe to read the book over a nice cup of coffee. One of the simple pleasures of life...
That's just how I tend to buy ebooks. I browse the genre list on Amazon, check out the most popular or best selling ebooks or just browse through the lists. Then I download a sample if the book sounds interesting and is above my impulse buy price.
I'll also take a look at books other people are reading though or check out the books amazon may recommend based on purchase history. Not often I find a fit, but it doesn't take long to look.
Reason I switched to ebooks is, convenience and no need to set aside space in the home to store all those books I don't want to part with. Plus instant download if I read a book and want to continue on with the series, no nipping to the shop to see if they have it in stock. Added benefit is the ability to take a library of books on holiday and not have to decide until I'm sat in bed one night or at the pool which book to read :P
One thing I wish authors and the stores would do more, is notify you of updates to the books and make it easy to download the latest version or an earlier revision.
Not for everyone though, I know a few people who have tried my kindle and earlier my hanlin but would rather keep buying paper (especially when they pickup paperbacks for next to nothing in the local supermarket)