Just a link dump, for now… starting with blog posts by @jgoerzen:
What if you live offline and have a phone to bring to the next access point, like a coffee shop in town?
All the devices at the remote location could communicate with each other. The Android app is quite capable of syncing photos and videos using Syncthing, for instance. Then one device could be taken to the Internet location and it would transmit data on behalf of all the others – perhaps back to a computer at your home, or to a server somewhere. Perhaps a script running on the remote server would then move files out of the syncthing synced folder into permanent storage elsewhere, triggering a deletion to be sent to the phone to free up storage. When the phone gets back to the other devices, the deletion can be propagated to them to free up storage there too. – A Simple, Delay-Tolerant, Offline-Capable Mesh Network with Syncthing (+ optional NNCP)
More about all the tools and technologies out there:
NNCP, on the other hand, lets you relay messages over TCP, a radio, a satellite, or a USB stick. Email and Usenet, since they were designed in an era where store-and-forward was valued, can actually still be used in an entirely “offline” fashion (without ever touching an IP-based network). All it takes is for someone to care to make it happen. You can even still do it over UUCP if you like. – Recovering Our Lost Free Will Online: Tools and Techniques That Are Available Now
NNCP a an be used for browsing in that you have the remote download web pages and all their dependencies, then sync them. Here are some links from the NNCP website:
Anyway, something to think about for the slow net.