I tried visiting these, and it's strange how similar they are. They don't seem to have ads, so I checked if they were minejacking, but it doesn't look like they are either. Inputing an address doesn't do anything, so they may be logging those, but I have no idea what they could use them for. Maybe they're just preparing something shadier for the future? Either way, it's probably best to not visit them, unless you know you have adequate protection.