Fax services
There are many online fax services.
FaxZero is handy. You can send a fax for free without any registration. However, it takes 5 to 10 minutes to send a fax, so it may not be suitable if you have someone waiting for your fax on the other end of your ongoing phone conversation. Its quality is not very good, so it may not suitable for documents with fine prints.
Dropbox Fax (a.k.a., HelloFax) is fantastic. It is quick, free, and has high quality.