Ich werde wohl mittelfristig auch keinen zweiten Mac zu Hause, im Büro oder bei Freunden zum Testen dieser Applikationen haben. Drum also als Notiz für später:

Desktop Transporter is an application that allows you to access your Macintosh displays remotely over a network, from a different Macintosh. It supports sharing of one or more displays attached to your Mac, and allows you to control access to it using a password.

Desktop Transporter discovers shared displays using Rendezvous, but also provides an option for specifying which machine it should connect to in cases where Rendezvous doesn't work. You can also set a number of options controlling the quality of the shared display.

Folgendes wäre vielleicht sogar noch interessanter, weil es eine Windows-Variante gibt, ich bin mit VNC aber eigentlich ganz zufrieden:

Bosco`s Screen Share is a new, easy way to share your computer’s desktop with your friends. Bosco’s Screen Share runs on Mac OS X, Mac OS Classic, and Windows, allowing you to share and drive desktops regardless of platform choice. Bosco’s Screen Share uses a peer-to-peer, serverless protocol and leverages standards such as JPEG image compression and TCP/IP, ensuring excellent performance with minimal interruptions. Bosco’s Screen Share can also work with Personal Web Sharing to publish your screen to friends' web browsers.

zumal das Ding als SHAREWARE mit US$ 25 auch nicht umsonst ist.