I would really like someone to kick-start radicle nodes over i2p. ( clearnet link : https://radicle.xyz ) It's like git, but decentralised. Imagine hosting uncensorable git repos that are distributed all over the network. Things like Nintendo shuting down emulators would not be possible. The idea behind it is basically made for I2P.

You would need however a webpage to advertise your node id and it's a little bit tricky to set-up over i2p. IDK, the current maintainer of the java version has proposed a tutorial that still hasn't made it on the official webpage : (another clearnet link : https://app.radicle.xyz/nodes/seed.radicle.xyz/rad:z371PVmDHdjJucejRoRYJcDEvD5pp/patches/18e6ec1dd5e87e39223ceade8e016107937ab1c3 )

Another fun thing to try out would be hosting a reticulum node over I2P ( https://reticulum.network ), which you can bridge with the clearnet. Reticulum is a network stack that allows you to have a network over essentially anything, from the regular internet, ham radios, LoRas, and yes, I2P. You can build networks of networks with it.

Then, tutorials... content in general. Looking for information not available on I2P that /is/ on the clearnet? Have a go and make a webpage about it!