You want to share a high-resolution scan of the family Bible pages with Uncle Stan, so you fire up your e-mail, attach the file, hit send—and your message immediately bounces back. Why? Either your or your recipient’s e-mail provider limits the size of attachments, usually to prevent large files from clogging the system.

Fortunately, there’s a convenient alternative: Online file-sharing services allow users to upload large files (think family books, scans, photographs, audio and video) to a site where other family members can access and download them. Most services offer password-protection so only specified recipients can view your files; some let you share files on social networking sites such as Twitter and Facebook. Our chart highlights free offerings from seven services; visit the sites to learn about upgrade options.