Shmoop is a very interesting site to say the least. Just by glancing at the name you can tell it is a little different, then when you start reading some of the content on Shmoop you can tell that these "guys" have a fun/good sense of humor.
What Shmoop is, is a site compiled of study guides for Literature/History/Poems. Also, it is a great resource for teachers/students to find: study tips/questions/links, etc. What I love most about Shmoop is the very user friendly layout which is easy to follow and it boasts some nice graphic design as well.
I do have an email into them regardding what their filtering policy might be, but I think it may not apply as users can't upload the content, only Shmoop themselves can.
For more info click here.