I recently came across the Aller Sans family of fonts and soon realised that they look really good when used on Ubuntu. I had previously been using Droid Sans, however I do now prefer this more elegant looking font.
To use them, first download the ZIP file them from the link at the bottom of this post. Once you have downloaded and opened the ZIP, extract all of the .TTF files from the ZIP into a temporary directory (you may delete them once finished). Then go through each file, opening it in the GNOME Font Viewer and then clicking ‘Install Font’ to install it.
Once you have done this, you are free to use them on Ubuntu, if you go to System>Preferences>Appearance>Fonts, you can set them as the fonts used in the Ubuntu interface. Below is a screenshot of how I have them configured.
Anyway I hope this was useful and now my question to you is:
What font do you use on Ubuntu?