Using email for almost everything from FTP downloads/uploads or Free WEB site hosting to using it for gatter FINGER or WHOIS information (telnet is still not available :)
Mailing lists are funneled into news groups. Gmane does spam detection, cross-post handling, has a TMDA-fueled encryption/forwarding service, a web interface, respects X-No-Archive, supplies RSS feeds, uses SPF, features user-defined filters, more...
Disposable temporary e-mail address which expire after 15 minutes. You can read and reply to e-mails that are sent to the temporary e-mail address within the given time frame.
page will generate a HTML encoded mailto link that is reasonably 'spambot' proof. Spambots crawl over websites looking for email addresses, when they find one they add it to their database for junk email.
an e-mail notification system that scans the entire Microsoft Knowledge Base every night, and e-mails you when updates or additions are made to the technologies you subscribe to.
a tool that simplifies the process of compressing and sending your files online. It isn't a replacement for the traditional desktop compression tools, but its just a tool that makes things easier by cutting down all the 'krunching' hassles.
cross-platform mail and news client. It is available for X11/Unix and MS Win32 platforms, supporting a wide range of protocols and standards, including SMTP, POP3, IMAP, NNTP (including SSL support for all of them) and full MIME support.
application that tells you when your emails have been received and opened. It works alongside your existing mail program, sending you an email the moment your message is viewed