For configuring the open-source graphics drivers when it comes to the screen resolution, managing multiple displays, and other display-related features, there's a host of options. Generally each Linux desktop environment has its own GUI solution for managing displays and they're all riding on RandR for communicating with the graphics drivers -- the open-source drivers and the closed-source AMD/NVIDIA drivers can all be configured in this way for display settings. Among the options are KScreen, GNOME Display Settings, etc.
When it comes to a GUI solution for managing other elements of the GPU/3D settings, that is where things are lacking. Windows converts and those using the binary AMD/NVIDIA drivers on Linux are accustomed to the the feature-rich Catalyst Control Center, Intel Display Settings, NVIDIA Settings, etc. From there you can easily and intuitively configure settings like anti-aliasing and aniostropic filtering, adjusting hardware-specific features like AMD OverDrive, read the GPU temperature and detailed information like the vRAM settings, and carry out a wealth of other tasks related to the graphics card. For the open-source Mesa/Gallium3D driver, there is just DRIConf.
DRIConf is a configuration applet for configuring DRI drivers and it's been around for a long time. DRIConf mostly just reads/writes to the drirc files for basic per-driver/per-application settings like v-sync, forcing GLSL extensions, MSAA, toggling S3TC, and other specific 3D features that can be toggled at run-time through the DRI configuration XML file or environment variables.
The Python-based program's GTK interface isn't very intuitive and not very user-friendly -- especially for recent Windows gamer converts -- but very much carries a developer feel to it. DRIConf also doesn't have any other features like thermal/fan-speed monitoring, detailed GPU hardware information, overclocking, etc.
Many of the features found in NVIDIA-Settings and AMDCCCLE on Linux aren't even supported by the open-source drivers like proper overclocking/underclocking, advanced anti-aliasing methods, etc. For the other information that is exposed and not displayed, you're basically left looking at text log files our the output of dmesg and other CLI-based utilities.
Here's a look at the AMD Catalyst Control Center on Linux:
And then the DRIConf as found via sudo apt-get install driconf on Xubuntu 13.10 with an Intel Haswell graphics processor:
The latest stable DRIConf release, v0.9.1, took place back in September of 2006. The code hasn't basically been touched in years, but you can find it at FreeDesktop.org.
Hopefully as more PC gamers and enthusiasts migrate to Linux, a new and properly-designed 3D driver configuration utility will be written that is more comparable to the solutions offered by the binary AMD and NVIDIA (and Intel Windows) drivers. There's also some features that would need to be added to the open-source drivers themselves for a GUI panel to reach parity with Windows in all the information that's exposed.
On a side note, for those into benchmarking, with Phoronix Test Suite 5.0 the GUI option is coming back and being rewritten and will offer many of the monitoring/information reporting features. The Phoronix Test Suite from the command-line already offers a wealth of system information reporting and system monitoring regardless of the driver in use as the Phodevi (Phoronix Device Interface) library already abstracts the calls between the AMD Catalyst driver, the NVIDIA Settings / NV_CONTROL interfaaces, and the information exposed by the open-source DRM/KMS and Mesa/Gallium3D drivers by different interfaces in a uniform manner. This will also continue to improve more with Phoronix Test Suite 5.0 for satisfying the needs of enthusiasts; the GUI monitoring though of course will not be GPU-only and pair elements of information similar to what's found on Windows with GPU-z/CPU-z and the former Motherboard Monitor 5.