More than 5,600 people available to answer the users' questions. Similar to Web Help. This is a registry of professionals who can serve as expert witnesses. No free answers from this group of experts. Lots of work to ask a question and get an answer.
Experts post answers to get credit.
This is a free service. Takes work to get useful information. Another credit-based site, but the credits are for telephone time. Users ask questions via the Web and then talk to experts to get answers. Another fee-based service.