It was interesting to read about the whole issue of the reference desk and the online answer websites. Looking at the question from the viewpoint of a school media specialist is somewhat different though. In the school media center, the media specialist is the reference desk. I receive many of the same reference questions as the public library and college library reference desk. The questions range from "can I use the restroom?" to "how can I find out how many slaves there were when the Civil War started?" to "how do I print this?" I don't get personal or relationship questions from my students (which is certainly OK with me!)
Online answer sites do provide anonymity which may be a large part of their appeal. I did notice that many of the questions asked on the Q & A sites I looked at were subjective or could have been answered by a Google search. Many of my students use Google as an answer site simply by typing their question into the search window. The students have mixed results.
I looked at allexperts and was impressed with the qualifications of the people who answered the questions I looked at. However, the organization of the site would make it difficult for an elementary student. Also, it looks like it covers lots more social topics than academic ones.
My fifth grade students recently used Answers.com to do some research for a scientist from the scientific revolution. I recommended that site because of the ease of citing their sources. Answers.com does provide citations for the students to copy and paste for each of their results which is wonderfully helpful. From there it was an easy switch to WikiAnswers. I discouraged that use because my students were trying to use it avoid reading the information they found on their Answers.com search. For example, they would search for "William Harvey's place in history" instead of reading one of the articles and having to think.
My role is to help teach the students to search for answers, do research and evaluate the results they get. Some of the answers sites may have some use there but I don't feel that my elementary students are good enough at evaluating the results yet to be encouraged to use those sites for schoolwork.