Posterous is a really quick way for you and your students to create blog posts or share videos/photos/audio with each other. The beauty of posterous is that you don’t need to go to the website to create the blog post, instead all you have to do is to email your text and/or photo to a designated email address and the website does the rest and creates the blog post for you. It's likely that most students should be able to do this directly from their mobile phones.
The best use I’ve found for it is as a way for my students to quickly send their photos from their mobile phones to a place where they can be seen by everyone in the class. My students often do interesting things at the weekend, travel to different cities, try different cultural experiences here in England and I thought this would be a great Monday morning warmer for students to share their experiences through the pictures they take. For example, one of my students today sent a picture of a international table tennis tournament she went to at the weekend
The other students were curious about this and asked her lots of questions, loads of interesting vocabulary came up (competition, winner, rounds, final/semi-final etc) and it was just a great 10 minutes of spontaneous chat and vocabulary generation at the start of the lesson. Every Monday I try to do this with at least one or two students and it really kicks off the week nicely.
Depending on the pictures, you can do different things. If it’s something unclear/obscure, you can ask the student not to say what it is and where it is and the other students have to guess. Or they can spend a few minutes creating questions they would like to ask the student about their picture.
Setting it up so students can post to the blog is not difficult at all. You just add their email addresses as Contributors in the Settings page and once they have the email of the site (which is usually an email version of the website name), they can send any pictures/text/audio recording via email and in a few minutes it will immediately pop up on the site as its own blog post.
Although I use it mainly for photographs, the fact that you can send text, audio and video means that it could be a great way for students to be really creative in documenting their lives and experiences and sharing them with the class via their mobile phones.