lpkfuse is a FUSE filesystem that lets you place all the SSH public keys of your users into LDAP. Without this tool, you would have to patch your SSH server (for example using openssh-lpk) to support this. But with lpkfuse, you just need to amend AuthorizedKeysFile in your sshd_config file. Other benefits include LDAP resilence and caching/local-fallback in case no LDAP servers are accessible.