Simply by asking this, I probably exclude myself from those who might benefit from Meerkat but: What can it be used for? I have minimal knowledge of SSH but gleaned more from this forum, yet more examples might help myself and others drawn to Meerkat about why it is the answer.
Yes: Connect securely to your home Mac's iTunes
Yes: Connect your computer securely to a server or another computer
If you don't have your own server space; e.g., www.mememe.com?
RSS feed retrieval and upload?
Are there hosting services that for whatever reason disallow SSH connections?
I've seen all the Meerkat videos, but I would like more examples. What does Meerkat need? What can Meerkat do and not do? I've just begun to play with it, so I might end up answering these questions for myself, but not for others.
No worries. I'll admit that Meerkat is a bit challenging if you don't already know what SSH tunnels are about. Its original intent was more of an assistant to folks who already use tunnels, and less an application to help introduce them to why they might want to.
Maybe it will help to think of it this way.
Think of most internet connections, such as a web browser connecting to a website. It connects to a hostname (the domain name) and a port, which for HTTP by default is 80. Similarly, POP is 110, IMAP is 143, etc.
Now suppose that from the network that you're on currently, you either can't reach website.com port 80, either due to routing problems or possibly a firewall specifically blocking it. Some examples might include a location blocking sites like Facebook, a network outage causing interruptions, or something like that.
Another use case might be that you want to contact website.com on port 80, but in an encrypted way, since you don't trust the network that you are on and port 80 traffic by default is not encrypted (unlike HTTPS port 443 traffic is).
You could use an SSH tunnel to establish a secure, encrypted connection between your local Mac, say on port 10080, through a machine someplace running an SSH server, to website.com port 80. Then, typing "http://localhost:10080" into your web browser would reach website.com port 80 using the SSH server as an intermediary.
That's the basic premise and what Meerkat helps automate and keep active. With Meerkat, you could actually bookmark "http://localhost:10080" in your browser and use Meerkat to ensure that anytime your browser was running, the tunnel would be there to allow a connection.
Does that help?
Since this introduces an intermediary, it is technically a slower connection, but in exchange for being able to connect when you otherwise wouldn't be able to, or to connect securely instead of insecurely, perhaps it is worth it.
Here's one more set of scenarios for which SSH tunnels with Meerkat could be useful.
Support you have a home or office computer that is always on and you'd like to access an iTunes library on it.
When you are outside of that location, the Mac with the library is probably obscured from the internet at large because of a router and/or firewall on that network. It might have a private IP address like 192.168.0.143 that is not generally routable from the wider internet.
If you are able to SSH into that computer from the outside using the router's port forwarding abilities, you can forward any number of services out to where you are currently. Combining the automation of that with Meerkat's ability to broadcast Bonjour services, you could make it look like the service tucked away behind that router is right here next to your Mac.
Something like this:
local Mac ==> externally-available SSH server inside the office ==> iTunes server inside the office
In this case, you'd be tunneling into an SSH server (say, 192.168.0.125) and telling it to make 192.168.0.143's port 3689 (iTunes port) available locally.