We have a nifty Chrome extension called the Toggl Button. It creates a little Toggl button inside your favourite webapp (Asana, Pivotal Tracker, Github and Teamweek supported at the moment), and lets you start the timer without switching a page.
Feel free to get Toggl Button from Chrome webstore.
Edit. Toggl Button is an open-source project, so anybody can contribute to adding new tools and features. Asana link was created by fellow developer rubinsh, and direct link to the source code is available here – https://github.com/toggl/toggl-button/pull/2
Thank you rubinsh, we really appreciate your effort!