Tools designed to help out when you're working with SSH tunnels:

• tunnels that get automatically restarted
  • autossh — automatically restart SSH sessions and tunnels
  • rstunnel — automatically restart SSH sessions and tunnels
• ssh triggered from xinetd
  • short article
  • short article
  • longer article
  • [writeup] SSH tunnel on demand
• semi-automatic multi-hop SSH
  • Transparent Multi-hop SSH
  • wow, this is nice ^^^
• apps that will semi-automatically work on top of SSH tunnels
  • tightvnc — its "-via" option is the SSH username/host to proxy through (NICE!)