I received a 'love letter' from my hosting provider: you have too many tables in your databases and are negatively impacting performance. You have 14 days to correct this or we will take your firstborn...or something to that effect.
Of course, the Drupal Community isn't the only place to give back. It's a complex world, and there are as many worthy causes as their are melodies, with most being served by multiple charitable organizations. Here are a few of those that strike a 7th chord with me.