Chrome has them, Firefox has them and, soon, so will GNOME 3. What am I wittering on about? Web apps.
GNOME Web Apps
The late September release of GNOME 3.2 will provide, amongst others updates and features, a†“web application mode”†for GNOME’s default web browser ‘Epiphany‘.
The GNOME approach to creating web apps is simple: you save website as a web app via a menu entry or by pressing CTRL+A. Web apps†created this way behave just like a traditional app on the GNOME desktop: they can be launched from the Activities overview, pinned to favourites, etc.
GNOME Web apps sport a minimal interface,†displaying not a jot more than a title bar and your chosen site.
Neater still, GNOME web apps become independent of Epiphany and run as a separate process: if Epiphany crashes or freezes your web app will remain unaffected.
Web apps are also sandboxed; if you try to follow a link within the web app that goes to a different website or service that link will, instead, open up in Epiphany and thus not affect your web app.
More information on this feature, along with credit for the images used above, can be found @†blogs.gnome.org