I've resurrected rosproxy, which is a hack I wrote several months ago to enable access to services and topics within a protected network. It's written in Python, so it's not super efficient, but it's useful when interfacing your robot with an external website or the like.

For example,

Internal network:

rosrun test_ros talker.py & 
rosparam set proxy/topics [chatter]
rosparam set proxy/xmlrpc_port 11313
rosrun rosproxy proxy.py

External network:

rosrun rosproxy register.py pub /chatter std_msgs/String http://externalname:11313
rostopic echo chatter
---
data: hello world 1286321252.19

Another related hack I did awhile back is ronin, which is a "masterless node". This is useful if you need to keep a node attached to a graph that is going up and down, e.g. if you want to pull data from a robot whenever it is up.

Both of these are "experimental" and will likely never be fully stabilized, but they are fun starting points and show some of the hackability of ROS.