Teachers; interested in connecting with businesses that can offer educators resources? Listed below are some websites/establishments that make education a priority.
Businesses; interested in contributing to the education system? Why? Well, it's good karma, the right thing to do and the PR doesn't hurt either.
Consider a webpage on your site for Educators/Students that might contain contact information or details for:

Field trip visits to your business
Guest presentation options in classrooms or assemblies
Teacher discounts for products or services
Interview availability of staff members for student projects
Sponsorship possibilities for activities
Inernships or shadow days for high school/college students
University student project possibilities
Donation programs requirements
Creating lesson plans in your field of interest or resources
Creating pamphlets or educational units for free classroom use
Kids section with resources that are age appropriate with interesting facts and info

Ideas for participating can be as simple as meeting a student for an interview, visiting a 6th grade class studying inventors with your inventions, speaking at an assembly, being an exhibit for an Earth or Technology Day activity, allowing a group of students to visit or tour - and so much more. Hands on meeting real people is the best education for students at any grade level. Almost all state and federal government agencies have a kid's page. Teachers and schools have very limited budgets so these offerings are best done as freebies. My advice is not to offer anything you can't actually commit to. When you are contacted, a quick response gives you some credibility. Schools are often willing to thank you in the parent newsletters that are sent home, although the smiles from the kids should be enough. Believe me, there isn't a parent that won't hear about what you did in school, so make sure you do a good job ! I would not suggest doing it for the PR, but because you want to contribute to the efforts made by educators everywhere.
Some companies that do this very successfully are listed below as links to their educational resources.

MicroSoft Educators
Denver Post's Education Page
Intel's Education Initiative
AT&T Blue WEbn Education
Discovery School - Kathy Schrocks Guide for Educators
PBS Teacher Source
Waste Management
Disney
General Motors
Scholastic's Teacher Resources
Smithsonian Education for Educators
Library of Congress Learning Page
National Science Digital Library
4frontiers
National Geographic Expeditions  
Hershey Corporation
HP's Create a Scape and environmental educational programs
New York Times Lesson Plan Archives
Pfizer Brain lesson and Green Chemistry Education Tools (middle school lessons)
Peace Corps Lesson Plans
IBM
Barnes & Nobel / Staples / Borders teacher discounts card for classroom books or materials