If you want a solution like ssh which needs to run through an http proxy then the suggestion of just putting an ssh server on a webby port probably won't help, because the proxy will try to parse ssh and get horribly confused.

Instead, you need to wrap the ssh protocol in http. You want to use httptunnel, which lets you wrap *any* protocol in http. No need to use https of course, because while the wrapper might be plain-text, the ssh packets encapsulated therein are still nicely opaque.

httptunnel can be downloaded from here.