MeMaker is a simple open-source tool that allows you to create cool avatars to use in wherever you like, ie forums, facebook, twitter, chat room, image boards ... The package's size is very small but it has many options and features. You can choose various styles for your avatar: plazmoid, cocohead, artistic, glyphface, animal-crackers, plastidudes and free-styles. When creating your avatar, there are also many different types of hair, eye, mouth, face shape ... for you to choose to make your avatar unique. After finishing the avatar, you can save it as PNG, BMP, SVG or Gnome avatar. The exported images will have a transparent background.
Here is an avatar I created with the Freestyle style:
And another one with the Artistic style:
Since MeMaker is in the repository of Ubuntu and Linux Mint, if you are using one of these distros, you can search for it in the Software Center or use the following command to install it:
sudo apt-get install memaker
If you are using Arch Linux, here is the aur package of MeMaker
If you are using other distros, here is the source package of MeMaker