Sometimes (you have a modem but you're offline; the servers are sucking; you're in early development and are sending lots of complete cruft) it's nice to have a nearby LJ server under your control. You could, of course, install a real one, but that's pretty heavy.
As a completely low-tech alternative (you only need Apache), try flat, the mock LJ server. It's a CGI you point your client to (your client can be pointed to alternative servers, right?), and it sends trivial canned responses to login and other protocol requests.
It's totally simple now, and only does the two protocol modes I needed at the moment. But I suppose I'll be adding stuff to this occasionally, and it's very easy to add more things yourself, so try it out occasionally.