KeePass features a plugin framework. Plugins can provide additional functionality, like support of more file formats for import/export, network functionalities, backup features, etc.
You can download the latest KeePass plugins from http://keepass.info/plugins.html.
Plugin Installation and Uninstallation
If the plugin doesn't provide explicit instructions how to install it, follow these steps:
In other words, to "install" a plugin you simply need to copy it into the KeePass directory.
To "uninstall" a plugin, delete the plugin files.
What about the security of plugins? Can't malicious plugins 'inject' themselves into KeePass?
If plugins can register themselves (i.e. have write access to the KeePass directory), they could also just replace the whole KeePass.exe. It's rather a problem of file access rights, not the plugin system.
If you worry about this, install KeePass as administrator into the program files directory (which is the default, typically in a folder in 'C:\Program Files (x86)'). Afterwards, run KeePass and other applications only as normal user (without administrator privileges).
This solves the problem above. As the KeePass directory is write-protected for normal users, no other program can copy files into it. KeePass requires the plugins to be in the application directory. Therefore, plugins cannot inject themselves anymore.
If you use the portable package of KeePass or installed it into a different directory, you need to adjust the directory permissions yourself.