Many authors are considering epublishing. Epublishers produce your writing in an electronic format that is bought and downloaded by readers instead of published in a hard copy. There are advantages and disadvantages to this and Margaret Riley, epublisher of Changeling Press, gives and overview of the process at BookEnds, LLC.'s blog.
She makes some great points. It can take years in traditional publishing to get an agent, sell your book, and then finally get that 5,0000 or 10,000 advance. In the meantime you get nothing.
However if you publish short novellas around 20,000 words on a regular basis, you might make $500 within a few months. No advance up front - it's all based on sales. But your books continue to sell as you publish new ones, and the checks can be steady. But of course you don't get the respect that comes with publishing in print.
That attitude may change one day, but it hasn't yet. One number I saw said epublishing sales are up 1,000% over last year. It's a market with big growth potential, and Amazon and other publishers are starting to get on board.
From what I've seen, genre rules in ebooks. Erotica, sci fi, and supernatural romance are big categories right now, but many companies publish non-fiction and other genere fiction too. EPIC, an organization for electronically published authors, has a list of epublishers to check out. I am assuming they've vetted them, but always do your own research to make sure the companies are reputable and pay on time.