SSH can be used to:
The most frequent (and perhaps most important) use; password security is of upmost importance, especially with the popularity and relative ease with which brainless morons (i.e., crackers) can sniff data off a network. The distributed and cooperative nature of the Internet is good for service and accessibility, but horrible for security... if you want security, you must take steps to make it work, and SSH is a very useful tool to that extent.
Not as useful... frankly, most people are just boring. But if you want to use PGP, SSH (again from the remote machine), passwd or some other interactive program which requires you to send or receive sensitive information, SSH will keep that data secure as it's being sent from|to the remote machine to|from the local machine over the network.
To be fully secure, however, one must look at all the places where their password is sent out over the network (and is thus available for capture by a malicious party). Besides telnet| rlogin connections, two other common services which require passwords are FTP and POP. In both these cases, the password is sent over the network in clear text. However, SSH includes the ability to use these services in an encrypted manner, thus disallowing the sending of sensitive information over the network.
SSH is currently being deployed across campus. SSH is available on UCB's undergraduate CS machines and socrates.berkeley.edu. As well, uclink[234]?.berkeley.edu will be supporting SSH in the near future. Your local system administrator can be contacted to determine the availability of (or to encourage the installation of) SSH on other machines. An issue of Berkeley Computing & Communications contains an article on SSH in relation to the UCB campus environment.