A network-accessible service enables participating end users to collaborate with one another over a network. End users have computing devices (e.g., computers, mobile phone, tablet devices, or the like) that include hardware and software to enable the device to access a network, such as the public Internet, a Wi-Fi network connected to the Internet, a 3G or higher wireless network connected to the Internet, a private network, or the like. The network-accessible service provides a publicly-available site (such as a Web site) or a local software application from which a first participating end user initiates a “meeting,” e.g., by selecting a “share” button. In response, the site or software application provides an HTTP link that includes a “meeting” code, which may be a one-time unique code. The first participating end user then shares the link with whomever he or she desires to collaborate. Upon receiving the link (e.g., by e-mail, instant message, SMS, MMS, orally, or the like), a second participating end user joins the meeting “on-the-fly” by simply selecting the link or navigating to the site and entering the “meeting” code (in a “join” field). The service connects the second participating end user to the meeting immediately and without requiring any registration, software download, or the like.