An increasingly common technique, I think appropriated from PDF and other document viewers (Google Maps?), is the draggable interface. http://www.fichey.com/ is a site that implements this navigation method.
This kind of thing allows for innovative two dimensional navigation, especially if you use Flash to make the movement fluid. Fichey and others that use a Flash solution miss a critical element, especially give the rather massive size of their grids - and that is bookmarking.
A simple solution would be to have Flash parse the GET request to look for a “coord” value. If your site implements so-called clean URLs, make the x and y coordinates the last sections in the URI.
That way a user can link their friends directly to the area in question and bookmark it to return to later - both a critically important to usability.