Live Blockchain Backup
The easiest way would be doing a snapshot, but this method depends mainly on OS or Hardware support.

Another option is creating a bootstrap.dat file, which is basically a concatenation of all blocks in a single file. When the node finds this file in its data dir it loads all blocks from it before connecting to the network, so the initial load can be much faster (again, depending highly on your IO and processing capacity...).

You can create a bootstrap.dat file using the tools here. To restore, see https://bitcointalk.org/index.php?topic=145386.0