I've always liked this project.
They have a solid model for renting and providing data storage. Their hosting costs claim to be significantly cheaper than Amazon S3.
Siacoin is used to rent hard drive space and get paid for providing spare hard drive space. This is a logical use of the coin and there are no other weird uses like yield farming.
In order to be a host, you have to put up some Siacoin as collateral. If your uptime is less than 98% or you lose data files, then your host ranking goes down. You also lose coins from your collateral if you aren't able to fulfill your hosting contracts.
This is all very fair and makes sense. Everything is spelled out for both renters and hosts.
Minus 1 star because I haven't actually used this solution to host data or provide spare hard drive space, but everything I see looks really good. Show Less