While I have quite a few free adult image hosts for you to consider here on My Gay Sites, I do realize that my loyal readers have come to expect a lot of variety when push comes to shove. For that reason, I decided that PostImage.org was another worthy destination that you may want to consider as being your go-to host for sharing pictures online.
Key positive features include the ability to resize the content, deletion rights and an account function that allows you to organize your content with very little effort. On the down side, PostImage.org doesn't really have that much mass-file upload capability: you can't submit a ZIP file, for instance. Still, it's capable of grabbing images for URLs you provide, so if you want a backup of images from a particular location, it's quite easy to get them.
The site has an App for desktop users on Windows systems as well as the ability to integrate simple uploads on a dozen different platforms for your users.