Harpseals.org will have an exhibitors booth at WorldFest which is LA's largest EarthDay Festival. You can check out their website for a map, etc at: www.worldfestevents.com
Here's more details:
The WorldFest 2008 Earth Day Festival will be held on Saturday, May 10th, 2008, from 10 am to 6:30 pm, at the beautiful outdoor setting of Woodley Park in Encino, CA. We will welcome our attendees to a magnificent day filled with entertainment, education and enlightenment. The combination of great music, empowering speakers, environmental, humanitarian and animal welfare non-profits, kid's activities and an delicious food court make for an earth-friendly experience that is sure to be inspiring and enjoyable for all.

Here's What's Happening at WorldFest this Year:

Main Stage - bigger-name bands and celebrity speakers.
Earth Lounge - singer/songwriters, jazz, rock, funk, and world music groups and poets.
EcoTent - speakers, discussions, and displays about sustainable living and current environmental issues
Healthy Hut - speakers, discussions, and displays about health including yoga, meditation, and cooking demos.
Exhibitors - over 100 companies showcasing their products and organizations.
Kids' World - storytelling, face painting, and children's entertainers and other activities!
Oasis Beer and Wine Garden - Refresh yourself in the Oasis located near the Main Stage!
Animal Adoptions - dogs, cats, rabbits and lots of animals looking for good homes!