Use the adjective worthy to describe the good causes to which you donate a little money each year. Their admirable qualities are what make them worthy.
Something that deserves respect is worthy, whether it's a charity, a hard working tennis opponent, or a struggle to overcome a disability. If it's worth your admiration or has some inherent value, it's worthy. The word has been around since the thirteenth century, and it was especially common in the 1300's to use worthy as a noun meaning "person of merit."