The Novella Project is an ebook publisher of novellas of 20,000 to 35,000 words. They publish only one story each quarter of the year. The site doesn't mention genre so I expect they're looking for more literary work. Payment is $100 advance on the first 100 downloads. After that royalties will be paid quarterly at the rate of $1 per download. They want exclusive rights for two years, non-exclusive after that. You can find the details here http://thenovellaproject.com/submission-guidelines/
UPDATE: 1/6/13 The Novella Project closed up shop.