Use a random code in the url (8 letters/digits should be enough) so that they can access their space on both desktop and mobile devices. It's kind of like mailinator.com where you can create fake email addresses. The only thing is that if you use an existing name, you can read the content of that user. Maybe that's ok for your use case?
Write StoryWrite an article on something you learned today or your experience with a technology
Ask QuestionStart a discussion, ask a question, or ask for an opinion on a particular technology
Start PollConfused with something? Ask the community for their opinion
Submit NewsFound an interesting article on the web? Share it with the community.