XUL

XUL is a new ISP technology used for making front-ends to Web applications and browser plug-ins. It's not an ISP service per se and can be used with any ISP provider so long as they allow direct access to Web files. XUL files can be downloaded just like XHTML or CSS files (and in fact typically work hand-in-hand with both XHTML and CSS files). They define graphical interfaces that go beyond the capabilities of raw XHTML and CSS. The end result is that Web sites with XUL can give much better user experiences than sites without XUL, but since XUL is new it won't work with every browser.