Here is a way to copy an entire filesystem without descending down its subsumed mount points. This example uses the root filesystem:

$ find / -xdev | cpio -pm /desired/location

Tagging is useful for taking snapshots of releases. For example, in /path/to/project:

$ svn copy trunk tags/release-1.0
$ svn commit -m 'Created release 1.0 tag.'

You can use the xclip utility to manipulate the X clipboard from the commandline or from a script. This command will overwrite the current X clipboard selection with the contents of /etc/passwd so a subsequent paste will contain the text of the file:

$ xclip < /etc/passwd

Download source from http://people.debian.org/~kims/xclip/.