A simple ssh tunnel to save you lot of trouble with accessing machines on a private network behind a gateway. Assuming you can ssh into a normal user account on a gateway, you can setup a ssh SOCKSv5 proxy on your machine so that other programs can access machines on private LAN via SOCKS v5 proxy.
Note: I use tortoiseplink as it goes to background completely.
To ssh into machines on private network, configure putty to use the above configured proxy.
You can even tunnel your browser via this SOCKS v5 proxy. This can be a very useful feature if you are on a untrusted network, like wifi in airport, and want to access sensitive website via a known clean Internet connection.