Considering the time some of us spend staring at text on our Ubuntu Linux installs, having blurry fonts in Ubuntu can be a major issue. While font appearance is a subjective opinion there are a couple things we can look at to see if we can get our Ubuntu fonts to render the way we would like them to.
Your Monitors Native Resolution
Lets forget for a moment that how the Ubuntu fonts look in general is a subjective opinion. There are a few things that will cause your Ubuntu fonts to appear blurry. One of the biggest issues I have seen that will cause the Ubuntu fonts to appear blurry, as well as the rest of the GUI, is not running their monitor at the native resolution. While some people will say that there are no issues with forcing your monitor to run at a non-native resolution, I disagree wholeheartedly. Modern LCD monitors, in particular, have a native resolution for a reason. Running them at any other resolution can cause distortion in the images it produces. This distortion, in many cases, will cause what users describe as "blurry fonts" in Ubuntu.
The fix for this is a simple one. Consult your monitors user manual to find out it's native resolution and use it! If your monitors user manual says it's native resolution is 1680×1050 and you find out that Ubuntu's screen resolution is set to 1600×1200 (or any other resolution aside from the native for that matter) change it to match your monitors native resolution. The result of this small change can be a huge one, depending on how far off your Ubuntu resolution was from your monitor's native resolution. Tolga Balci, another writer here at BrightHub, recently had this problem with his NVIDIA driver. He was unable to adjust his display settings to match his monitors native resolution which was causing blurry Ubuntu fonts. If you are using the NVIDIA driver and configuration tool be sure to start the configuration tool with root privileges so it can write the modified xorg.conf file. Thanks to Tolga for his HubFolio blog post on this subject.
Ubuntu Appearance Preferences
Under the appearance preferences pane you will find a font tab. On this tab you can make a few changes to the way fonts are displayed on your Ubuntu system. You will want to make sure the subpixel smoothing radio button is ticked if you are running an LCD monitor to ensure the best possible default font rendering on your Ubuntu system. On this same tab you will see a details button, clicking this button will bring up another preference pane with additional font rendering options. Resolution, smoothing, hinting, and subpixel order can all be modified here. In Ubuntu 9.04 the default hinting value has been changed from full to slight eliminating many of the complaints about blurry fonts. In earlier versions of Ubuntu this value always defaulted to full, which some say, caused fonts to appear blurry. To be totally honest, with the latest release of Ubuntu most of the font problems should be eliminated for the everyday user. Users who are still experiencing blurry Ubuntu fonts in 9.04 or users using an earlier release of Ubuntu may want to check out some of the links provided in the next section which outlines a few forum and blog posts with tips on how to improve your font rendering in Ubuntu. Keep in mind that people have had mixed results at best with some of these tactics which involve the modification of configuration files.
Martin Ankerl has an interesting blog post here that details his experiences with font rendering in Ubuntu 8.10 and 9.04. His recommendations include modifications to the ~/.fonts.conf and ~/.Xresources files and is completely safe assuming you make backups of any files you plan to modify.
Johan Kiviniemi also has a blog post here talking about how he doesn't like the default font rendering in Ubuntu since 8.04 and how he goes about fixing what he considers to be his blurry Ubuntu fonts. Again, be sure to backup any files you plan on modifying and you can always revert to your original settings should you not like the change.
This Ubuntu forum post contains a lengthy discussion on how to turn on a hinting feature that is disabled by default due to patent issues with Apple and what benefits, if any, you will see by making the change. Simply download the file attached to the first post and integrate the information into your ~/.fonts.conf file (if already present) or rename the file and place it in your home directory.