I have made the following personal contributions:
-Several pages to the handbook.
-Dozens (hundreds?) of small bug fixes and improvements to contrib modules and core
-Some direct module development (someday I'll be like Earl Miles, a.k.a. merlinofchaos)
-$40 to the Drupal tip jar.
-Drupal Association Member

My company, Prometheus Labor Communications, Inc., supports Drupal financially:
-We were $1000 sponsors for the 2008 Boston Drupacon
-We have paid many thousands of dollars to various Drupal developers through donations and contract work for code that was contributed back to the community.