Many online selection systems require a lot of interaction with a computer screen on the part of the applicant, and not so much (or sometimes any) human contact. This can be frustrating for applicants and can reflect poorly on your organization.
Check out this article to learn about “Humanizing the Online Application Experience”: http://talentmgt.com/articles/view/humanize-the-online-application-experience
Interested in a really in-depth look at selection best practices? Check out this report from The Center for Creative Leadership: http://www.ccl.org/leadership/pdf/research/ExecutiveSelection.pdf