For those who can't open the site, here's what they say about submissions (on the "Contact Us" page:
Editorial submissions
Send query letters and submissions to:
Attn: The Editors
The Overlook Press
141 Wooster Street
New York, NY 10012
However, if you’d like your work to be considered for publication by The Overlook Press, we recommend that you work with an established literary agent. Agents can be found in such literary guides as Literary Marketplace.
We do not accept query letters and submissions via e-mail.
Here are the categories given on the "books by category" page of their site:
architecture / design
art / photography
biography / autobiography
business / current affair
calligraphy
children's books
cookbooks
fantasy / science fiction
fashion
fiction / literature
film / drama
gardening / horticulture
gay and lesbian interest
health / fitness
history / military history
humor
lifestyle / house and home
martial arts / sports
music / popular culture
mystery / thriller
new age
pets
philosophy / religion
poetry
pottery / ceramics
psychology / self-help
reference / how-to
regional interest
science
travel