I know this is an old topic but dialup fidonet/USENET/BBS and radio APRS services especially the APRS BBS and mailbox on the ISS are good examples of ultra low bandwidth but extremely useful data services.
If the rules were set to 160 character per message, a bounce message to people sending larger messages, and perhaps a maximum number of posts and mails per day/week/month/year period to limit bandwidth.
Combine with a SMS, APRS, OSCAR-APRS, email(with oversize bounce), or web gateway and a extremely valuable service to a person or remote community can be offered with them responding when they are in a location with or gain/borrow access to upstream telecommunications.
Delivering an updated alt maybe misc (and obviously trimmed to exclude /bin and other big data usegroups) but keeping at least a set aside othernet newsgroup as well as a mail feed encrypted or public plaintext would have been huge to me in the times that I had to live without any telecom beyond sometimes a pager and a 2m handheld.
Until othernet becomes so big that commercial sponsors and multiple transponders on several satellites come into use delivering limited short mail service and some form of usenet would be both an excellent use of the feed as well as drawing far more interest as it personalizes the experience despite being a broadcast and a very minimal percentage of the overall feed.
