It's not fully decentralized and more focused on reducing bandwidth load on the actual site than anonymity or resilience, but the sadpanda's H@H system is one example of such a thing: https://ehwiki.org/wiki/Hentai@Home

e: this is mainly interesting because it demonstrates that there are people willing to donate storage/compute/bw to p2p nsfw image hosting, not because the underlying tech is particularly revolutionary or should be used as a model for future systems