Take a look at tools listed and described in "Graphical Interfaces" section of Interfaces, frontends, and tools page on Git Wiki.
Beside gitk (history browser) and git gui (commit tool), both distributed with Git and both written in Tcl/Tk, there are among others the following graphical interfaces for Linux:
- QGit, which uses Qt toolkit, in C++
- Giggle, which uses GTK+ toolkit, in C
- git-cola, written in Python, uses PyQt4 toolkit
- gitg, a clone of GitX for GTK+/GNOME, in C
- tig (Text-mode Interface for Git), uses ncurses, in C
There is also git-instaweb to browse your working repository using gitweb.