Providing temporary use of on-line non-downloadable software for providing real estate listings and information, for contact management, for creating customized e-mails and managing e-mail campaigns, for creating and managing real estate advertising, for generating web-based forms, for tracking the sharing of real estate documents, for managing to-do lists for real estate professionals, for tracking and reporting website usage data, and for interacting with customers and potential customers, and interacting with customers and potential customers, namely, managing sales pipelines and workflows, all of the foregoing in the field of real estate