This was submitted to plugins.b2evolution.net back when we were using comments to accept plugin requests:
Comment from: Tony [Visitor] · http://www.mybossisacock.com · Edit
I want vistors to be able to upload pics with some story text for me to blog...Anything?
Postnuke has something like this. Unregistered users can post a story and it basically goes into a moderation queue. In b2evolution it would be added with a status of 'Draft.' This probably wouldn't be too hard of a pluting to create. A quick workaround would be to create an account that can only post drafts, and publish the username and password on your site.
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I did something similar once for a hobby site. I did not allow them to upload images because my goal was to allow people into the hobby but not in our club the ability to post. One thing I did was to give out clues to the user name and password so only fellow enthusiasts would be able to figure them out. One of the easiest hacks you could do, except it wasn't a hack - just using b2evolution a little bit differently is all.
Hey ya know what? b2evolution already has a demouser in it! Reckon most people delete good old Demo right away, but it's something for fresh installations to think about.