Most current web frameworks (speaking circa 2005) utilise HTTP and HTML (or younger replacements) in order to present a user interface remotely. However, these technologies have some drawbacks in terms of the kind of user interface which can be provided.
RichInternetApplications is one contender for providing a solution to this problem. Other, older options also exist. For example, the X Window System which has been used to display user interfaces remotely on UNIX systems for decades.
Please add such alternative options to this page!