I like to enter photo contests to motivate myself to keep photographing, and open myself to ideas for new concepts and subjects. Listings of tons of different competitions:
Other sites with individual contests:
- Art of Photography Show (San Diego)
- Art Show
- Bodie Foundation Calendar Contest
- Contemporary Art Gallery Online
- Darkroom Gallery
- F-Stop Magazine
- Gallery Photographica
- lacda
- Light Space & Time
- Linus Art Galleries
- National Geographic
- Nature Conservancy
- North County Society of Fine Arts (San Diego)
- Oceanside Museum of Art
- Outdoor Photographer
- Photoburst
- Smithsonian
- Terabella Media
- Women's Caucus for Art