Is there a plugin or some setting in EGit to show the current git branch in the toolbar of eclipse so that it's visible on which branch you're working?
Like Sasikanth says there is no toolbar in EGit that shows the current branch.
Since there usually are multiple repositories within your IDE, a toolbar that shows the current branch of a single repository would probably often choose the wrong repository to display.
But if you have an idea how such a toolbar could work you may want to open an enhancement request.
In the meanwhile you can either use the Repositories View to see the current branch of each repsoitory or look at the Pakckage Explorer or Project Explorer. The projects are decorated with the repository they belong to and the current branch that is checked out.
Here the project belongs to the gitexample
repository on branch master
.