Contact museums, libraries and historic audio archives if your reel-to-reel tape contains culturally significant music, reportage, commercials or other unique audio footage. Call or email the reference desk at your local public or university library, which can direct you to institutions that might be interested in your tapes.
Phone music and sound-engineering departments at local high schools, community colleges and universities, which might be able to use your reel-to-reel tape in their courses and programs.
Contact nonprofit music organizations, such as Musicians Workshop, VH1 Save the Music Foundation, Sound Exchange, National Music Foundation and ARChive of Contemporary Music, which might be able to use your tapes in conjunction with their programs, seminars and events.
Donate your reel-to-reel tapes to nonprofit thrift stores in your area. If you have many boxes of tapes, ask whether the organizations might be willing to pick them up from your home or workplace.
Post an ad in the "Free" section of on an online classified site such as Craigslist or in your local newspaper. If you ask people to respond with how they will use the tapes, you'll have some assurance that they'll be put to good use.